Silicon rubber vulcanization system and method based on SF6 waste gas plasma reduction treatment

Abstract

The invention discloses a silicone rubber vulcanization system and method 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 cylinder are sequentially communicated through a gas path, the separation gas chamber is connected with the mixed gas chamber through a dilution gas chamber, and flowmeters 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. The ultraviolet light source is used for providing illumination for the discharge system and the vulcanization system, a catalyst is arranged in the discharge system, and SF waste gas, hydrogen and diluent gas can be introduced into the mixed gas chamber. According to the method, the S element in the SF6 waste gas can be efficiently utilized, the S is deposited in a simple substance form through catalytic degradation of SF6, meanwhile, the S is used as a vulcanizing agent to realize vulcanization treatment on a silicon rubber base material in real time, finally, the S element in the waste gas in the SF6 is converted into vulcanized silicon rubber in a vulcanization cross-linking form, and the purpose of resource utilization of the S element in the SF6 waste gas is achieved.

Description

Technical Field

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

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

[0003] SF6 degradation and resource utilization are the most direct and effective means to reduce SF6 waste gas emissions. However, most existing degradation technologies focus on the thoroughness of SF6 dissociation, and pay very limited attention 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; thermal catalysis can reduce the reaction temperature by adding catalysts, but at the expense of some degradation rates; low-temperature plasma methods can achieve efficient SF6 dissociation at room temperature and pressure, but the product regulation process is relatively difficult.

[0004] Regarding SF6 degradation treatment, the recent Chinese invention patents CN113082952A "A sulfur hexafluoride degradation treatment device and method based on sliding arc discharge" and CN115554823A "Sulfur hexafluoride degradation device based on thermal plasma" disclose degradation methods based on sliding arc discharge and thermal plasma torches, and CN115999358A "A sulfur hexafluoride degradation device" and CN115845600A "A sulfur hexafluoride waste gas harmless treatment system in an electrical insulator" disclose degradation treatment devices based on thermal catalytic cycles or series connection, respectively improving the SF6 degradation process in terms of degradation efficiency, energy efficiency and degradation adequacy. However, in the above methods and other related methods, most of the main toxic products produced after degradation are absorbed by alkaline material reactions and converted into salt substances with low economic value, and the utilization of S element is not mentioned, resulting in serious element waste. Summary of the invention

[0005] In order to solve at least one of the problems existing in the prior art, the present invention proposes a silicone rubber vulcanization system and method based on SF6 waste gas plasma reduction, which uses low-temperature plasma to catalytically reduce SF6 and realize the vulcanization of silicone rubber materials, and can efficiently utilize the S element in SF6 waste gas. By plasma catalytic degradation of SF6, S is deposited in the form of a single substance, and the silicone rubber base material is vulcanized in real time as a vulcanizing agent, and finally the S element in the SF6 waste gas is converted into the vulcanized silicone rubber in the form of vulcanization crosslinking, so as to achieve the purpose of resource utilization of the S element in SF6 waste gas. The present invention has the characteristics of high degradation efficiency, good stability, less carrier gas consumption, complete SF separation, and full utilization of the S element.

[0006] In order to achieve the aforementioned invention object, the present invention provides a microwave plasma-based SF6 waste gas degradation and silicone rubber vulcanization system, comprising a mixing gas chamber, a discharge system, a vulcanization system, a separation gas chamber, a collection gas cylinder, a dilution gas chamber and an ultraviolet light source.

[0007] The mixing gas chamber, the discharge system, the vulcanization system, the separation gas chamber, and the collection gas cylinder are connected in sequence by gas paths, and the separation gas chamber is connected to the mixing gas chamber through the dilution gas chamber. Flow meters and solenoid valves are arranged between the mixing gas chamber and the discharge system, between the mixing gas chamber and the dilution gas chamber, and between the separation gas chamber and the dilution gas chamber. The ultraviolet light source is used to provide illumination for the discharge system and the vulcanization system. A catalyst is arranged in the discharge system, and SF exhaust gas, hydrogen gas, and dilution gas can be introduced into the mixing gas chamber.

[0008] Furthermore, an SF6 waste gas source, an H2 hydrogen gas source and a dilution gas source are also provided, wherein the SF6 waste gas source is pretreated, or is pretreated by a conventional waste gas purification method and then connected to the mixed gas chamber, the H2 hydrogen gas source is directly connected to the mixed gas chamber, and the dilution gas source is connected to the mixed gas chamber through a flow meter and a solenoid valve, and is connected in parallel with the dilution gas chamber on the gas path.

[0009] Furthermore, it also includes a washing chamber and a drying chamber, wherein the washing chamber, the drying chamber and the mixed gas chamber are connected in sequence, wherein a flow meter and a solenoid valve are arranged between the drying chamber and the mixed gas chamber.

[0010] Acidic impurity gases, water vapor, solid particles, etc. in SF6 waste gas can be removed by conventional means such as alkaline adsorbents and wet scrubbing. The airflow is introduced into the mixing gas chamber after pretreatment.

[0011] Furthermore, in the SF6 waste gas purification pretreatment, the alkaline solution can be NaOH, KOH, Ca(OH)2, NaHCO3, etc., which is used to treat common impurity gases such as SO2, SOF-type gases, H2S, CS2, etc. in the SF6 waste gas source. Solid particles such as activated alumina and activated carbon can absorb a small amount of water washed in the SF6 waste gas source. A small amount of solid particles carried in the air flow can be cleared through gas path deposition, and the SF6 waste gas source entering the mixed gas chamber should have a high SF6 purity (>99.9%).

[0012] Furthermore, the dilution gas is any one of Ar and He.

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

[0014] SF6 gas is connected to the mixed gas chamber through the first flowmeter and the first solenoid valve, and SF6, H2, and Ar are mixed in the mixed gas chamber. Among them, the SF6:H2 ratio is set between 6.5 and 7.0, and the SF6 concentration is controlled between 2 and 10%. It is generally recommended to select 5%, and the rest is dilution gas. It is recommended to select rare gases such as Ar or He as dilution gas. It is generally not recommended to select N2, because N2 will participate in the discharge dissociation of SF6 in small amounts to generate NF x (x<4) and other greenhouse gases. If the SF6 concentration is selected as the recommended value of 5%, the H2 concentration is controlled between 32.5% and 35%, and the dilution gas concentration is controlled between 60.0% and 62.5%. The concentration ratio of the ternary mixed gas can be adjusted according to the actual flow rate through the flow meter.

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

[0016] Furthermore, the inner walls of the discharge system, the vulcanization system and the gas collection cylinder in contact with the gas are all provided with anti-corrosion coatings or anti-corrosion material devices.

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

[0018] Furthermore, the end of the discharge system is connected to the sulfurization system in the gas path, and the sulfurization system is physically below the discharge system to facilitate the deposition of S element.

[0019] Furthermore, in the discharge system, the catalyst is recommended to be a metal-loaded catalyst, wherein the carrier is recommended to be aluminum oxide or titanium oxide, the loaded metal is recommended to be non-precious metals such as copper or nickel, and the catalyst particle size is recommended to be at the cm level.

[0020] Furthermore, for the discharge system and the vulcanization system, the walls of the device are made of quartz glass or other transparent high-temperature resistant materials, and an ultraviolet light source is set at 5 to 20 cm outside the two devices, with a wavelength of 180 to 320 nm, which is used to promote the activation and degradation of SF6 and the vulcanization reaction of silicone rubber prepolymer, respectively, to accelerate the reaction and improve energy efficiency. The air 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 the S element and the vulcanization time of the silicone rubber, wherein the mass portion of the S deposition element is controlled at 3 to 4 parts and is directly vulcanized with the silicone rubber prepolymer for 6 to 8 hours.

[0022] Furthermore, the vulcanization system includes vulcanization devices such as a flat plate vulcanizer.

[0023] Furthermore, a distillation tower is arranged in the separation gas chamber and is equipped with a temperature control device.

[0024] Furthermore, a compression pump is provided inside the dilution gas chamber, and the introduced gas is temporarily stored at a pressure of 1.5 to 2 atmospheres. The mixed gas is passed into the mixed gas chamber through the control of a flow meter and a pressure reducing valve, thereby realizing the recycling of the dilution gas.

[0025] The top of the separation chamber is provided with an outlet, which is connected to the dilution chamber through a flow meter and a solenoid valve. A gas compression pump is provided in the dilution chamber to collect and compress the Ar and H2S separated in the separation chamber. The pressure of the dilution chamber is maintained at 1.5 to 2.0 atmospheres. The other side of the dilution chamber is connected to the mixing chamber through a flow meter and a solenoid valve to realize the recycling of the dilution gas and ensure that the H2S byproduct in the system participates in the next round of SF6 reduction reaction.

[0026] The present invention provides a silicone rubber vulcanization method based on SF6 waste gas plasma reduction treatment, comprising the steps of:

[0027] SF6 waste gas is mixed with H2 and dilution gas in a preset ratio in the mixing gas chamber and introduced into the discharge system for reduction through plasma discharge;

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

[0029] The product enters the vulcanization system, in which a silicone rubber prepolymer is arranged, and the S element is deposited from the gas phase to the solid phase in the vulcanization system, and the S element is added into the silicone rubber vulcanization process as a vulcanizing agent;

[0030] The treated tail gas in the vulcanization system is introduced into the separation chamber, where the temperature is controlled. The difference in liquefaction temperature of different gases is used to make HF liquefied and deposited and introduced into the collection chamber for collection. The dilution gas, a small amount of H2S, and the residual SF6 and H2 gas are circulated through the dilution chamber.

[0031] The S element produced by SF6 discharge degradation is continuously vulcanized with the silicone rubber prepolymer under the promotion of ultraviolet light to finally obtain vulcanized silicone rubber.

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

[0033] (1) The present invention realizes energy-efficient dissociation of SF6 based on low-temperature plasma coupled catalyst, promotes efficient and sufficient reaction of SF6 / H2, and realizes effective separation of SF elements.

[0034] (2) The S element of the present invention is reduced and deposited, and then used as a vulcanizing agent in the silicone rubber vulcanization process, thereby realizing the resource utilization of the 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 the airflow to provide a heat source for the vulcanization system, thereby achieving the purpose of saving energy consumption.

[0036] (4) The present invention plays a dual role of promoting by adding an ultraviolet light source and utilizing the optical properties of SF6 dissociation and silicone rubber vulcanization / interface reaction, thereby reducing the energy consumption of SF6 degradation and vulcanization treatment and improving 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. The degraded gas directly participates in S deposition and silicone rubber vulcanization, thereby improving the heat (energy) utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0040] Figure 2Schematic diagram of a silicone rubber vulcanization system in the form of microwave discharge in an embodiment of the present invention.

[0041] Figure 3 Schematic diagram of the processing flow in an embodiment of the present invention.

[0042] In the figure: 1. Mixing gas chamber; 2. First flow meter; 3. First solenoid valve; 4. Discharging system; 5. Vulcanization system; 6. Separation gas chamber; 7. Collecting gas cylinder; 8. Second solenoid valve; 9. Second flow meter; 10. Dilution gas 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 DESCRIPTION

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

[0044] See also Figure 1 The embodiment of the present invention provides a silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment, which can use the S element generated by plasma reduction of SF6 waste gas as a vulcanizing agent to achieve silicone rubber vulcanization. The system includes a mixing gas chamber 1, a discharge system 4, a vulcanization system 5, a separation gas chamber 6, a collection gas bottle 7, a dilution gas chamber 10, an ultraviolet light source 13, and gas path control devices such as solenoid valves and flow meters, wherein SF6 waste gas, H2 pure gas, and dilution gas (such as Ar) can be introduced into the mixing gas chamber 1.

[0045] The mixing gas chamber 1, the discharge system 4, the vulcanization system 5, the separation gas chamber 6, and the collecting gas bottle 7 are connected in sequence, and the discharge system 4 is located above the vulcanization system 5. The separation gas chamber 6 is also connected to the dilution gas chamber 10 through a pipeline. The dilution gas chamber 10 is connected to the mixing gas chamber 1 through a pipeline. A first flow meter 2 and a first solenoid valve 3 are arranged on the pipeline between the mixing gas chamber 1 and the discharge system 4. A second solenoid valve 8 and a second flow meter 9 are arranged on the pipeline between the separation gas chamber 6 and the dilution gas chamber 10. A third flow meter 11 and a third solenoid valve 12 are arranged on the pipeline between the mixing gas chamber 1 and the dilution gas chamber 10. The ultraviolet light source 13 is used to provide the discharge system 4 and the vulcanization system 5 with the required light for work.

[0046] The mixed gas chamber 1 is also connected to a H2 gas source.

[0047] The preliminarily purified SF6 waste gas is introduced into the air inlet end of the mixed gas chamber 1. In addition, the mixed gas chamber 5 is respectively connected to the first solenoid valve 3, the H2 gas source, and the third solenoid valve 12, so that the pretreated SF6 waste gas, H2 pure gas and the dilution gas are introduced and mixed in a preset ratio. In some embodiments of the present invention, the volume of the mixed gas 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 rest is filled with the dilution gas Ar. After the gas is mixed, it is controlled by the first flowmeter 2 and the third solenoid valve 3 to pass into the discharge system 4. The total flow rate of SF6 / H2 / diluted gas is controlled at 10-30L / min n.

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

[0049] The discharge system 4 includes a discharge reactor and its grounding system, a power supply, a reaction gas path, and a heat sink. The specific components of the discharge system can be purchased from domestic manufacturers. The high-voltage end and the low-voltage end of the power supply are respectively connected to the high-voltage electrode and the grounding system of the discharge reactor to provide the high-voltage input required for discharge. The heat sink is arranged around the discharge reactor and the plasma power supply. In some embodiments of the present invention, the heat dissipation form is mainly air cooling, which is used to maintain the working temperature of the plasma power supply and adjust the ambient temperature of the discharge reactor. Among them, the discharge reactor is a plasma reactor.

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

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

[0052] In some embodiments of the present invention, metal oxide-loaded metal catalyst particles are added to the discharge reactor. The carrier may be aluminum oxide or titanium oxide, etc., which has a higher dielectric constant to promote discharge and has better corrosion resistance. The loaded metal may be non-precious metals such as copper and nickel. The particle size is recommended to be at the cm level to ensure sufficient gaps for airflow to pass through and prevent it from hindering the S elemental sedimentation process.

[0053] In some embodiments of the present invention, the flow rate of the mixed gas of SF6 / H2 / diluent gas is controlled at 10-30 L / min during the discharge process, depending on the SF 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, 293g of SF6 waste gas can be processed in theory within 1 hour, and 64.3g of S element (sulfur) can be converted.

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

[0055] The vulcanization system 5 is a place 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 air chamber 6 .

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

[0057] In the vulcanization system 5, the mass fraction of S deposited element (sulfur) can be controlled at 3 to 4 parts, and directly vulcanized with the prepolymer at a vulcanization temperature of 160°C. After 6 to 8 hours of processing, a vulcanized silicone rubber product is obtained. In some embodiments of the present invention, a preset mass of silicone rubber prepolymer (the product after rubber mixing) is pre-placed in the vulcanization system 12, and the mass fraction of S element in the vulcanization treatment is 3 (total 100). The vulcanization system 12 performs direct vulcanization at a vulcanization temperature of 160°C. After 6 to 8 hours of processing, a vulcanized silicone rubber product is obtained.

[0058] Due to the excessively high reaction temperature in the discharge system 4, the S element flows out in a gaseous state through the reaction gas path with the airflow, and can directly contact the silicone rubber prepolymer. The vulcanization system 5 is provided with a temperature control device, which obtains the heat generated in the discharge system 4 through airflow transmission, and the system temperature is controlled at about 160°C. The main products after discharge degradation are S element, H2S, HF, and the remaining H2 and SF6. Adjusting the SF6:H2 ratio can ensure that the remaining H2 and SF6 gases are at a low concentration level. H2S is generated when excessive H2 is added to cause excessive reduction of the S element. Under the above-mentioned large gas velocity, the S element can be quickly solidified during the purge process with the prepolymer, and the remaining gas will be passed into the subsequent separation chamber 6. Among the remaining gases, only HF has a certain reactivity, but it is in a gaseous state and has a high gas velocity, and the reaction with the silicone rubber prepolymer will be very limited, and a small amount of silicone rubber surface fluorination process is conducive to improving its surface hydrophilicity and charge dissipation properties, and has no obvious negative impact on the overall vulcanization process.

[0059] In some embodiments of the present invention, silicone rubber prepolymer is obtained by plasticizing, mixing, extruding / calendering silicone rubber and auxiliary materials. The above pretreatment technologies are 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 vulcanization system 5 by a gas path, and the interior of the separation chamber 6 is a distillation tower equipped with a temperature control device. In some embodiments of the present invention, the separation chamber 6 can operate under normal pressure, and the temperature is controlled at -20 to 0°C, so that hydrogen fluoride HF (liquefaction temperature 19.54°C, 1atm) is liquefied at the bottom, while the dilution gas Ar (liquefaction temperature -185.8°C, 1atm) and H2S (liquefaction temperature -60.28°C, 1atm) exist in the form of gas at the top, so as to achieve gas separation. Ar and a small amount of H2S are passed from the top of the separation chamber 6 into the dilution chamber 10 through the second solenoid valve 8 and the second flowmeter 9.

[0061] One side of the dilution gas chamber 10 is connected to the separation gas chamber 6, and the other side is connected to the mixed gas chamber 1. A compression pump is arranged in the dilution gas chamber 10 to collect the dilution gas and a small amount of H2S gas remaining after discharge, and compress the collected Ar and H2S. The pressure is maintained at 1.5 to 2 atmospheres. The dilution gas chamber 10 is connected to the mixed gas chamber 1 through a third flow meter 11 and a third solenoid valve 12. The mixed gas can be introduced into the mixed gas chamber 1 to realize the recycling of Ar. H2S has reducing properties and can react with SF6 to generate HF and S single substance deposition, thereby being added to the reduction reaction of SF6 to realize secondary treatment with H2S.

[0062] The airflow circulating in the vulcanization system 5 passes through the air outlet and enters the air inlet located on the side of the separation chamber 6. The upper part / top and the lower part / bottom of the separation chamber 6 are respectively connected to the dilution chamber 10 and the collecting gas bottle 7 through gas paths. After discharge, the airflow acting in the vulcanization system 5 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 tower. 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. Ar and a small amount of H2S are passed from the top into the dilution chamber 10 in a gaseous state for storage, and HF is separated at the bottom and passed into the collecting gas bottle 7 in a liquefied form for storage.

[0063] In some embodiments of the present invention, during operation, a UV light source 13 is placed approximately 5-20 cm away from the discharge system 4 and the vulcanization system 5, and the light source is kept turned on during the SF6 gas discharge degradation and vulcanization system treatment process, providing 180-320 nm UV light with a light source power of 6000 uW / cm 2 It can promote the activation and degradation of SF6 and the vulcanization reaction of silicone rubber prepolymer, thus 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 to provide an implementation case of SF6 deposition of S element based on microwave plasma reduction treatment to achieve silicone rubber vulcanization. The embodiment system is as follows Figure 2 The system is also provided with a washing chamber 14 and a drying chamber, the washing chamber 14, the drying chamber 15, and the mixed gas chamber 1 are connected in sequence, and a fourth flow meter 16 and a fourth solenoid valve 17 are provided on the pipeline between the drying chamber 15 and the mixed gas chamber 1. Figure 2 and Figure 3 The specific processing process of the system is as follows:

[0065] (1) SF6 waste gas pretreatment: The SF6 waste gas is passed into the washing chamber 14 for wet washing. 40L of saturated Ca(OH)2 solution is placed in the washing chamber 14. The washed SF6 waste gas is passed into the drying chamber 2, where the water in the gas flow is removed by adsorption by activated alumina. During the treatment process, the flow rate of the SF6 waste 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 diluent gas Ar gas source supply gas to the mixed gas chamber 1, SF6:H2=1:7, H2 flow rate is controlled at 5.25L / min, Ar flow rate is 24L / min, the total flow rate at the outlet of the mixed gas chamber 1 is about 30L / min, and the SF6 concentration is about 5%.

[0067] (3) SF6 discharge reduction treatment: Control the first flowmeter 2 and the first solenoid valve 3 to pass the SF6 / H2 / Ar mixed gas 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, the input power is controlled at 5kW, and the center temperature of the microwave discharge reactor is about 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 partitions. In the microwave discharge reactor, SF6 is reduced by H2 to S element and HF, as well as a small amount of H2S, and the SF degradation rate is not less than 99%. The discharge gas flow is sprayed from the top to the bottom of the microwave discharge reactor, and the tail gas after the reaction is passed into the vulcanization system 5 through the bottom gas path of the microwave discharge reactor. During the discharge degradation, the ultraviolet light source 13 is kept turned on at a distance of 15cm and provides light in the 180-320nm band.

[0068] (4) Silicone rubber vulcanization treatment: The vulcanization system 5 includes a flat vulcanizing machine, and a silicone rubber prepolymer is pre-placed according to the conditions that the mass of S element (sulfur) is 192.9 g and the mass part of sulfur vulcanizing agent is 3, totaling 6430 g. The vulcanization treatment is carried out at 160°C for 6 to 8 hours to obtain a vulcanized silicone rubber product. During the discharge degradation, the ultraviolet light source 13 is kept turned on at a distance of 10 cm and provides light in the 180 to 320 nm band.

[0069] (5) The treated tail gas in the sulfurization system 5 includes Ar, HF, H2S and other gaseous products, which are separated and discharged into the separation chamber 6. The separation chamber 6 has a built-in distillation tower to keep the temperature of the separation chamber 6 at -20°C. HF is liquefied due to its high liquefaction temperature and deposited at the bottom of the separation chamber 6. Ar, a small amount of H2S, and the remaining SF6 and H2 remain in the gaseous state due to their low liquefaction temperature. They are discharged from the top of the separation chamber 6 and are controlled by the second solenoid valve 8 and the second flowmeter 9 to enter the dilution chamber 10. The remaining liquid HF gas is injected into the collection cylinder 7 with fluorine-proof coating for storage.

[0070] (6) Dilution gas and by-product circulation: A compression pump is provided in the dilution gas chamber 10 to pump and compress the Ar, H2S and other gases discharged from the separation gas chamber 6. After collection, the pressure of the dilution gas chamber 10 is maintained at a level not lower than 1.5 atmospheres, and is controlled to flow into the mixed gas chamber 5 through the third flowmeter 11 and the third solenoid valve 12 to ensure that in addition to the Ar gas source ventilation in the initial operation stage, the Ar in the system mainly comes from the circulating Ar stored and collected in the dilution gas chamber 15. H2S, SF6, H2 can control the SF6:H2 ratio to keep it at an extremely low level, generally H2S is less than 1%, SF6 and H2 are less than 0.1%, and the impact on the gas preparation in the mixed gas chamber can be ignored.

[0071] In the above-mentioned embodiment of the present invention, SF6 is reduced to S element and HF by H2 through purification pretreatment, ratio mixing, and discharge reduction; gas phase S is deposited through the vulcanization system and participates in the vulcanization reaction of the silicone rubber prepolymer as a vulcanizing agent, and a vulcanized cross-linked silicone rubber product is obtained through vulcanization treatment. The remaining gases are liquefied and separated based on the difference in liquefaction temperature, and finally the S element deposition and reuse, HF liquid phase recovery, and the recycling of dilution gas and byproduct H2S are realized.

[0072] The specific embodiments described herein are merely examples of the principles and methods of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner, such as changing the low-temperature plasma discharge form, the geometric dimensions of the reactor, the type of tail gas absorption medium and the absorption treatment sequence, the injection method and the mixing ratio, etc., as well as changing the type of prepolymer for silicone rubber vulcanization, the temperature and pressure conditions, and the vulcanization time, etc., but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

Claims

1. A silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment, characterized in that: It comprises a mixed gas chamber (1), a discharge system (4), a vulcanization system (5), a separation gas chamber (6), a collection gas bottle (7), a dilution gas chamber (10) and an ultraviolet light source (13). The mixed gas chamber (1), the discharge system (4), the vulcanization system (5), the separation gas chamber (6), and the collection gas bottle (7) are interconnected in sequence, and the separation gas chamber (6) is connected to the mixed gas chamber (1) via the dilution gas chamber (10). Flow meters and electromagnetic valves are provided between the mixed gas chamber (1) and the discharge system (4), between the mixed gas chamber (1) and the dilution gas chamber (10), and between the separation gas chamber (6) and the dilution gas chamber (10). An ultraviolet light source (13) is used to provide illumination for the discharge system (4) and the vulcanization system (5). A catalyst is provided in the discharge system (4), and SF6 waste gas, hydrogen, and dilution gas can be introduced into the mixed gas chamber (1).

2. A silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that: The dilution gas is any one of Ar and He.

3. A 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 and dielectric barrier discharge.

4. A 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 vulcanization system (5) and the gas collection cylinder (7) that are in contact with the gas are all provided with anti-corrosion coatings or anti-corrosion material components.

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

6. A 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 less than 800°C 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 the S element and the vulcanization time of the silicone rubber, wherein the mass of the S deposition element is controlled at 3 to 4 parts and 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 arranged at a preset distance outside the discharge system (4) and the vulcanization system (5), and the wavelength of the ultraviolet light source (13) is in the range of 180 to 320 nm.

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

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

Images