Thermal plasma-based harmless degradation method and system for SF 6
By decomposing SF6 gas with thermal plasma jets to generate HF, the problem of poor degradation of SF6 gas under static conditions is solved, achieving efficient and safe harmless treatment of SF6 and reducing gas consumption and product processing difficulty.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- GUIZHOU POWER GRID CO LTD
- Filing Date
- 2025-02-27
- Publication Date
- 2026-05-15
AI Technical Summary
In existing technologies, the degradation effect of SF6 gas in a static environment is limited, the products are acidic and toxic gases, and the dilution process leads to gas waste, affecting the treatment efficiency.
SF6 gas is decomposed using thermal plasma jet. H2 is used as the reactant gas to capture the released F atoms and generate HF, which prevents SF6 association reaction. N2 and Ar are used as carrier and protective gases, respectively. Plasma is generated by high-frequency power supply to achieve the harmless degradation of SF6.
It improves the degradation rate of SF6, reduces gas consumption, significantly enhances the degradation effect, makes the generated HF easier to remove, and improves the safety and efficiency of the treatment process.
Smart Images
Figure CN2025079510_15052026_PF_FP_ABST
Abstract
Description
A method and system for the harmless degradation of SF6 based on thermal plasma Technical Field
[0001] This invention relates to the technical field of SF6 treatment, and in particular to a method and system for the harmless degradation of SF6 based on thermal plasma. Background Technology
[0002] SF6 is a synthetic gas in which the central sulfur atom is stably connected to the six surrounding fluorine atoms by covalent bonds, forming an octahedral configuration. SF6 gas itself is colorless, odorless, non-toxic, non-flammable, and slightly soluble in water. It is chemically very stable, has strong electron affinity, and can undergo a self-restoration process after bond breakage, thus possessing excellent insulation and arc-quenching properties.
[0003] SF6 is widely used in the power industry as an excellent gaseous insulating material, and it is also used as a protective gas in semiconductor processing and ore smelting. Although SF6 has many excellent properties, its efficient absorption of infrared radiation in the 915-960 cm-1 band will lead to a serious greenhouse effect. It is listed as one of the six limiting gases in the Kyoto Protocol. Its greenhouse potential is 23,500 times that of CO2, far exceeding other greenhouse gases.
[0004] SF6 can exist stably in the atmosphere for up to 3200 years, decomposing slowly only under ultraviolet light. Therefore, the large-scale emission of SF6 waste gas poses a serious threat to the atmospheric environment. For the discharge treatment of SF6, the mainstream methods are to use dielectric barrier discharge, thermal plasma discharge, microwave discharge, etc., to form a plasma region in a designated reactor to decompose SF6 gas. In the "Experimental and Simulation Study on Dielectric Barrier Discharge Plasma Degradation of SF6" published in the Proceedings of the Chinese Society for Electrical Engineering in 2017, Zhang Xiaoxing et al. of Wuhan University used a quartz glass reactor to achieve DBD discharge treatment of SF6 waste gas. During the treatment process, SF6 needs to be diluted, and nitrogen and air are commonly used as dilution gases. Finally, a degradation effect of more than 90% can be achieved.
[0005] However, in this method, SF6 gas is degraded under static conditions, and the products are mainly acidic and toxic gases, which limits the emission. Other scholars who have studied the electrolysis process of SF6 waste gas also need to dilute the SF6 gas. Excessively high concentrations of SF6 gas will inhibit the discharge process and weaken the treatment effect. As a result, a large amount of gas needs to be consumed in the dilution process, which leads to gas waste. Therefore, this problem needs to be solved. Summary of the Invention
[0006] In view of the problems existing in the above-mentioned SF6 harmless degradation methods and systems based on thermal plasma, the present invention is proposed.
[0007] Therefore, the purpose of this invention is to provide a method and system for the harmless degradation of SF6 based on thermal plasma.
[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for harmless degradation of SF6 based on thermal plasma, comprising: inputting SF6 and reactive gas into a reaction chamber; the plasma jet generated by the thermal plasma torch in the reaction chamber gradually decomposes SF6 into atoms; the reactive gas captures the released F atoms to generate HF, while preventing SF6 association reaction, thereby achieving SF6 degradation.
[0009] As described in the present invention, the SF6 harmless degradation method based on thermal plasma is H2 as the reaction gas.
[0010] As a preferred embodiment of the SF6 harmless degradation method based on thermal plasma described in this invention, the working gas used in the thermal plasma torch is N2 and Ar, wherein N2 is used as the carrier gas and Ar is used as the protective gas.
[0011] As a preferred embodiment of the SF6 harmless degradation method based on thermal plasma described in this invention, when the working gas enters the thermal plasma torch, it is ionized by a high-frequency power supply to form plasma.
[0012] As a preferred embodiment of the SF6 harmless degradation method based on thermal plasma described in this invention, when the working current of the thermal plasma torch is 100A and the carrier gas flow rate is 10L / min, the plasma formed by ionization will become a stable laminar thermal plasma with a jet length of up to 45cm.
[0013] As a preferred embodiment of the SF6 harmless degradation method based on thermal plasma described in this invention, the high-frequency power supply adopts an AC voltage source to provide the thermal plasma torch with a 10kHz high voltage of 2-4kW, a maximum power of 500VA, and a frequency of 20kHz.
[0014] A thermal plasma-based SF6 degradation system, applied to the aforementioned thermal plasma-based SF6 degradation method, comprises:
[0015] The gas distribution section is used to control the output of SF6, N2, Ar, and H2;
[0016] The reaction chamber is equipped with a thermal plasma torch and has an air inlet and an air outlet, wherein the air inlet is connected to the gas distribution section.
[0017] The processing section is connected to the gas outlet of the reaction chamber;
[0018] The gas distribution section delivers metered N2, Ar, SF6, and H2 to the reaction chamber. The thermal plasma torch is excited by a high-frequency power supply, ionizing N2 and Ar to form a plasma jet. The plasma jet gradually decomposes SF6 into atoms, and H2 captures the released F atoms to generate HF. The processing section absorbs and processes the generated HF.
[0019] As a preferred embodiment of the SF6 harmless degradation system based on thermal plasma described in this invention, the gas distribution section includes:
[0020] The gas storage unit consists of four gas tanks, which independently store N2, Ar, SF6 and H2 respectively.
[0021] The gas distributor has its inlet end connected to the gas storage unit and its outlet end connected to the inlet on the reaction chamber.
[0022] As a preferred embodiment of the SF6 harmless degradation system based on thermal plasma described in this invention, there are three air inlets, all of which adopt annular channels. The outlet of the gas distributor is connected to the three air inlets one by one through three branch pipes. The air inlet of the gas distributor is connected to four gas tanks through a main pipe and four manifolds.
[0023] As a preferred embodiment of the SF6 harmless degradation system based on thermal plasma described in this invention, the treatment section includes:
[0024] The exhaust pipe has its inlet end connected to the outlet end.
[0025] The bag filter has an inlet end connected to the outlet end of the outlet pipe.
[0026] The alkali tower has its inlet end connected to the outlet end of a bag filter.
[0027] The cooling component is connected to the reaction chamber and the discharge pipe at both ends.
[0028] The beneficial effects of this invention are as follows: This invention decomposes SF6 into atoms using plasma jets, and then captures the released F atoms with the reactive gas to generate HF, while simultaneously preventing SF6 association reactions, thereby achieving SF6 degradation and effectively solving the problems of limited SF6 degradation rate and poor degradation effect. Attached Figure Description
[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:
[0030] Figure 1 is a schematic diagram of the framework of the SF6 harmless degradation system based on thermal plasma of the present invention.
[0031] Figure 2 is a schematic diagram of the gas distribution section in the SF6 harmless degradation system based on thermal plasma of the present invention.
[0032] Figure 3 is a schematic diagram of the treatment section in the SF6 harmless degradation system based on thermal plasma of the present invention. Detailed Implementation
[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0035] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0036] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.
[0037] Example 1
[0038] A method for harmless degradation of SF6 based on thermal plasma includes introducing SF6 and reactive gas into a reaction chamber 200. The plasma jet generated by the thermal plasma torch in the reaction chamber 200 gradually decomposes SF6 into atoms. The reactive gas captures the released F atoms to generate HF, while preventing SF6 association reactions, thereby achieving SF6 degradation.
[0039] Compared to SF6, HF is easier to remove and degrade, thus solving the problem of SF6's difficulty in degradation;
[0040] Furthermore, the reaction gas used is H2. H2 is a clean energy source, and its combustion product is mainly water. It does not produce harmful greenhouse gases or other toxic substances. Therefore, using H2 can improve the safety of the entire degradation process when treating SF6.
[0041] Furthermore, the working gases used in the thermal plasma torch are N2 and Ar, with N2 serving as the carrier gas and Ar as the protective gas.
[0042] Furthermore, when the working gas enters the thermal plasma torch, it is ionized by a high-frequency power supply to form plasma.
[0043] The function of the thermal plasma torch is to generate arc plasma. During operation, Ar and N2 are input to ignite the arc. The thermal plasma torch draws an arc between the cathode and anode through the arc-starting nozzle, and maintains the stable combustion of the arc on the axis under the action of the tangentially rotating airflow. At the same time, the ionized gas is blown out to form a plasma jet. After the high-frequency power supply switches to the working state, N2 is replaced with H2, and SF6 is input. The input gas enters the discharge area of the thermal plasma torch through the gas flow meter at a specific value. SF6 is decomposed into atoms, and H2 captures the released F atoms to generate HF, while preventing the association reaction of SF6, thus realizing the degradation of SF6.
[0044] Specifically, when the SF6:H2 mixing ratio is set to 1:2, the DRE is 86.4%; when the mixing ratio is 1:3, the DRE increases to 87.5%; and when the mixing ratio is 1:4, the DRE increases to 98.6%.
[0045] The anode in the thermal plasma torch is an arc-initiating anode. When SF6 gas is introduced into the plasma torch, the arc voltage increases significantly, making it difficult to ignite and maintain the arc. Compared with ordinary single-anode plasma torches, the presence of an arc-initiating anode can reduce the arc-initiating voltage. In addition, the arc-initiating anode increases the arc length and arc voltage, enabling low current input and high power output, and expanding the plasma region.
[0046] Furthermore, when the thermal plasma torch operates at a current of 100A and a carrier gas flow rate of 10L / min, the ionized plasma will become a stable laminar thermal plasma with a jet length of up to 45cm. The laminar thermal plasma has a longer jet, better axial energy output, and more stable and quiet operation.
[0047] Furthermore, the high-frequency power supply uses an AC voltage source to provide the thermal plasma torch with a 2-4kW 10kHz high-voltage AC voltage, a maximum power of 500VA, and a frequency of 20kHz.
[0048] Example 2
[0049] Referring to Figures 1-2, this embodiment differs from the first embodiment in that: this embodiment provides an SF6 harmless degradation system based on thermal plasma, applied to the SF6 harmless degradation method based on thermal plasma in Example 1, which includes:
[0050] The gas distribution section 100 is used to control the output of SF6, N2, Ar and H2;
[0051] The reaction chamber 200 is equipped with a thermal plasma torch and has an air inlet 201 and an air outlet 202. The air inlet 201 is connected to the gas distribution section 100.
[0052] The processing section 300 is connected to the gas outlet 202 of the reaction chamber 200;
[0053] The gas mixing section 100 delivers metered N2, Ar, SF6 and H2 to the reaction chamber 200. The thermal plasma torch is excited by a high-frequency power supply, which ionizes N2 and Ar to form a plasma jet. The plasma jet gradually decomposes SF6 into atoms, and H2 captures the released F atoms to generate HF. The processing section 300 absorbs and processes the generated HF.
[0054] Furthermore, the valve train 100 includes:
[0055] The gas storage unit 101 consists of four gas tanks, which independently store N2, Ar, SF6 and H2 respectively.
[0056] The gas distribution instrument 102 has its inlet end connected to the gas storage unit 101 and its outlet end connected to the inlet 201 on the reaction chamber 200.
[0057] Specifically, the gas distributor 102's inlet is connected to four gas cylinders via a main pipe and four manifolds. The outlets of the four manifolds are all connected to the main pipe, which in turn connects to the gas distributor 102. Each manifold is equipped with a valve to control the gas output. These four valves control the output of N2, Ar, SF6, and H2 respectively. The discharged gas enters the gas distributor 102 through the main pipe and is then distributed by the gas distributor 102. The outlet of the gas distributor 102 is connected to the three inlets 201 via three branch pipes. Each unit is equipped with a valve for regulating flow rate. The gas after distribution is transported through three branch pipes and then enters the reaction chamber 200 through the inlet 201. There are three inlets 201 in total, and each adopts an annular channel. This distribution can generate tangential and axial velocities in the airflow, allowing the electric arc to continue rotating and passing through a larger area. When the electric arc rotates, the temperature distribution is uniform, which increases the airflow speed and improves the kinetic energy of the airflow. This allows the gas in the reaction chamber 200 to be fully decomposed, improving the SF6 degradation efficiency and producing less SFx. At the same time, it can reduce the noise generated when the airflow enters the equipment and improve the working environment.
[0058] The rest of the structure is the same as in Example 1.
[0059] Example 3
[0060] Referring to Figure 3, this embodiment differs from the above embodiments in that the processing part 300 includes:
[0061] The exhaust pipe 301 has its inlet end connected to the outlet 202;
[0062] The bag collector 302 has its air inlet end connected to the air outlet end of the discharge pipe 301;
[0063] The inlet of the alkali tower 303 is connected to the outlet of the bag filter 302;
[0064] The cooling component 304 is connected at both ends to the reaction chamber 200 and the discharge pipe 301, respectively.
[0065] Specifically, a concentration sensor is installed on the discharge pipe 301 to detect the concentration of SF6 in the gas. After being cooled by the cooling component 304, the gas passes through the concentration sensor for concentration monitoring. The monitored gas then enters the bag filter 302 to filter out elemental sulfur. The filtered gas then enters the alkali tower 303 for sedimentation treatment. NaOH liquid is sprayed in the alkali tower 303. The NaOH sprayed on the gas surface absorbs the HF generated after degradation. Compared with SF6, HF is easier to remove and degrade, thus solving the problem of SF6 being difficult to degrade.
[0066] Preferably, plastic fragments are added as packing material inside the alkali tower 303 to prevent HF bubbles from escaping.
[0067] Specifically, the cooling component 304 includes a heat exchange tube 304a and a cooling medium tank 304b. Both ends of the heat exchange tube are connected to the reaction chamber 200. The high-temperature gas flowing out of the thermal plasma torch flows out through the heat exchange tube 304a. The cooling medium tank 304b contains a refrigerant that coats the outside of the heat exchange tube 304a and exchanges heat with the high-temperature gas flowing in the heat exchange tube 304a. The cooled high-temperature gas has a lower temperature and enters the discharge pipe 301 for transportation, which can prevent the equipment from being damaged by high temperature.
[0068] The rest of the structure is the same as in Example 2.
[0069] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values (e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.
[0070] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the currently considered best mode for carrying out the invention, or those features that are not relevant to implementing the invention) may be omitted.
[0071] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.
[0072] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for the harmless degradation of SF6 based on thermal plasma, characterized in that: include, SF6 and reactive gas are introduced into the reaction chamber (200). The plasma jet generated by the thermal plasma torch in the reaction chamber (200) gradually decomposes SF6 into atoms. The reactive gas captures the released F atoms to generate HF, while preventing SF6 association reaction, thus achieving SF6 degradation.
2. The SF6 harmless degradation method based on thermal plasma as described in claim 1, characterized in that: The reaction gas used is H2.
3. The SF6 harmless degradation method based on thermal plasma as described in claim 2, characterized in that: The working gases used in the thermal plasma torch are N2 and Ar, with N2 as the carrier gas and Ar as the protective gas.
4. The SF6 harmless degradation method based on thermal plasma as described in claim 3, characterized in that: When the working gas enters the thermal plasma torch, it is excited by a high-frequency power supply, and the gas is ionized to form plasma.
5. The SF6 harmless degradation method based on thermal plasma as described in claim 4, characterized in that: When the thermal plasma torch operates at a current of 100A and a carrier gas flow rate of 10L / min, the plasma formed by ionization will become a stable laminar thermal plasma with a jet length of up to 45cm.
6. The SF6 harmless degradation method based on thermal plasma as described in claim 5, characterized in that: The high-frequency power supply uses an AC voltage source to provide the thermal plasma torch with a 10kHz high-voltage AC voltage of 2-4kW, a maximum power of 500VA, and a frequency of 20kHz.
7. A harmless degradation system for SF6 based on thermal plasma, characterized in that: The method for harmless degradation of SF6 based on thermal plasma as described in claim 1 includes: The gas distribution section (100) is used to control the output of SF6, N2, Ar and H2; A reaction chamber (200) is provided with a thermal plasma torch, and the reaction chamber (200) has an air inlet (201) and an air outlet (202), wherein the air inlet (201) is connected to the gas distribution section (100); The processing section (300) is connected to the gas outlet (202) of the reaction chamber (200); The gas distribution section (100) delivers metered N2, Ar, SF6 and H2 to the reaction chamber (200). The thermal plasma torch is excited by a high-frequency power supply, which ionizes N2 and Ar to form a plasma jet. The plasma jet gradually decomposes SF6 into atoms. H2 captures the released F atoms to generate HF. The processing section (300) absorbs and processes the generated HF.
8. The SF6 harmless degradation system based on thermal plasma as described in claim 7, characterized in that: The gas distribution section (100) includes: The gas storage unit (101) consists of four gas tanks, which independently store N2, Ar, SF6 and H2 respectively; The gas distributor (102) has its inlet end connected to the gas storage unit (101) and its outlet end connected to the inlet (201) on the reaction chamber (200).
9. The SF6 harmless degradation system based on thermal plasma as described in claim 8, characterized in that: There are three air inlets (201), all of which are annular channels. The outlet of the gas distributor (201) is connected to the three air inlets (201) through three branch pipes. The air inlet of the gas distributor (201) is connected to four gas cylinders through a main pipe and four manifolds.
10. The SF6 harmless degradation system based on thermal plasma as described in claim 9, characterized in that: The processing section (300) includes: The exhaust pipe (301) is connected to the air outlet (202) at the air inlet end; The bag collector (302) has its inlet end connected to the outlet end of the outlet pipe (301); The alkali tower (303) has its inlet end connected to the outlet end of the bag filter (302); The cooling component (304) is connected at both ends to the reaction chamber (200) and the discharge pipe (301).