Method and system for degrading SF6 based on placing copper ring on DBD inner electrode

Abstract

The invention relates to the technical field of SF6 treatment, and particularly discloses a method and a system for degrading SF6 based on placing copper rings on a DBD inner electrode, and the method comprises the following steps: conveying accurately proportioned and diluted SF6 into a DBD reactor, discharging an electrode bar in the DBD reactor to form an electric field, and changing a partial discharge gap and the electric field by using a plurality of copper rings on the electrode bar to complete the degradation of the SF6; according to the invention, diluted SF6 is sent into a plasma environment, SF6 molecules are bombarded by high-energy electrons, ionization and excited state molecules, a cracking reaction is carried out, a low-toxicity or non-toxic decomposition product is generated, and the generated decomposition product is more convenient for adsorption treatment compared with SF6, so that the consumption of diluted gas is reduced, the cost waste is reduced, and the degradation efficiency of SF6 is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of SF6 treatment, and in particular to a method and system for degrading SF6 based on placing copper rings on DBD inner electrodes. Background Art

[0002] SF6 is a synthetic gas. The central sulfur atom and the surrounding six fluorine atoms are stably connected by covalent bonds, forming an octahedral configuration. SF6 gas itself is colorless, odorless, non-toxic, non-flammable and slightly soluble in water. It has very stable chemical properties and strong electron affinity. It can undergo a self-recovery process after bond breaking, so it has excellent insulation and arc extinguishing properties.

[0003] SF6 is widely used in the power industry as an excellent gas insulation material. 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 915-960cm-1 band will lead to a serious greenhouse effect. It is listed as one of the six restrictive gases in the Kyoto Protocol. Its greenhouse effect potential is 23,500 times that of CO2, far exceeding other greenhouse gases. SF6 can exist stably in the atmosphere for up to 3,200 years and only slowly decomposes under ultraviolet light.

[0004] Therefore, the large-scale emission of SF6 waste gas poses a serious threat to the atmospheric environment. For the discharge treatment process of SF6, the mainstream method is to use dielectric barrier discharge, thermal plasma discharge, microwave discharge and other forms to form a plasma area in a designated reactor to decompose the SF6 gas. In 2017, Zhang Xiaoxing et al. of Wuhan University published "Experimental and Simulation Research on Degradation of SF6 by Dielectric Barrier Discharge Plasma" in the "Proceedings of the Chinese Society of Electrical Engineering". A quartz glass reactor was used to achieve DBD discharge treatment of SF6 waste gas. During the treatment process, SF6 needs to be diluted, and the dilution gas is usually nitrogen, air, etc., which can eventually achieve a degradation effect of more than 90%;

[0005] However, in this method, SF6 gas degrades in a static environment, and the products are mainly acidic and toxic gases, and the emissions are limited. Other scholars also need to dilute the SF6 gas when studying the electrolysis process of SF6 waste gas. Excessive concentration of SF6 gas will inhibit the discharge process and weaken the treatment effect. In this way, a large amount of gas needs to be consumed in the dilution process, resulting in gas waste. This problem needs to be solved. Summary of the invention

[0006] In view of the problems existing in the above-mentioned existing method and system for degrading SF6 based on placing copper rings on the inner electrodes of DBD, the present invention is proposed.

[0007] Therefore, the object of the present invention is to provide a method and system for degrading SF6 based on placing copper rings on electrodes within DBD.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for degrading SF6 based on placing copper rings on electrodes inside DBD, comprising: transporting SF6 diluted with precise proportions to a DBD reactor, discharging electrode rods in the DBD reactor to form an electric field, and utilizing a number of copper rings on the electrode rods to change the local discharge gap and electric field to complete the degradation of SF6.

[0009] As a preferred solution of the method for degrading SF6 based on placing copper rings in DBD inner electrodes according to the present invention, the inner diameter of the copper ring is consistent with the outer diameter of the electrode rod, the thickness of the copper ring is 1.6 mm, and the gap between two adjacent copper rings is 25 mm.

[0010] As a preferred solution of the method for degrading SF6 based on placing copper rings on electrodes inside DBD described in the present invention, the gas used to dilute SF6 is Ar, and its usage is: 98% Ar dilutes 2% SF6.

[0011] As a preferred embodiment of the method for degrading SF6 based on placing copper rings on electrodes inside DBD described in the present invention, the electrode rods in the DBD reactor are powered by a plasma power supply, and the plasma power supply adopts an AC power supply, which provides an AC voltage of 2-4kW at 10kHz.

[0012] As a preferred solution of the method for degrading SF6 based on placing copper rings in DBD inner electrodes according to the present invention, grounding wires are installed at both ends of the electrode rod.

[0013] A system for degrading SF6 based on placing copper rings on electrodes inside DBD, which is applied to the above-mentioned method for degrading SF6 based on placing copper rings on electrodes inside DBD, comprises:

[0014] The gas supply part is used to mix the Ar and SF6 mixed gas with the required concentration;

[0015] The DBD reactor has a plurality of copper rings equidistantly arranged on the electrode rod inside, and is provided with an air inlet and an air outlet;

[0016] The air inlet end of the absorption unit is communicated with the air outlet nozzle.

[0017] As a preferred solution of the system for degrading SF6 based on placing copper rings on electrodes in DBD according to the present invention, the gas supply part includes:

[0018] A gas storage unit, consisting of two gas tanks, which are used to store Ar and SF6 gas respectively;

[0019] The gas distributor has its gas inlet connected to the gas tank and its gas outlet connected to the DBD reactor, and is used to transport the proportioned Ar and SF6 mixed gas to the DBD reactor.

[0020] As a preferred solution of the system for degrading SF6 based on placing copper rings on electrodes in DBD according to the present invention, the absorption unit comprises:

[0021] Gas detector, used to detect the SF6 concentration in the exhaust gas from the DBD reactor;

[0022] The adsorption component is used for degrading and absorbing the exhaust gas from the DBD reactor.

[0023] As a preferred solution of the system for degrading SF6 based on placing copper rings on electrodes inside DBD according to the present invention, the adsorption component comprises:

[0024] tower body;

[0025] A liquid storage tank is arranged at the inner bottom of the tower body;

[0026] The packing layer is arranged in the middle section of the tower body and is used to absorb and clean harmful gases in the rising gas;

[0027] The spray head is used to spray the treatment liquid in the liquid storage tank from top to bottom, so that it contacts and settles with the rising gas.

[0028] As a preferred solution of the system for degrading SF6 based on placing copper rings on the inner electrodes of DBD described in the present invention, the treatment liquid is any one of water, alkaline solution or acid solution.

[0029] Beneficial effects of the present invention: The present invention sends diluted SF6 into a plasma environment, and SF6 molecules are bombarded by high-energy electrons, ionized and excited molecules, and cracking reactions occur to generate low-toxic or non-toxic decomposition products. The generated decomposition products are easier to adsorb and process than SF6, which reduces the amount of dilution gas used, reduces cost waste, and effectively improves the degradation efficiency of SF6;

[0030] Placing several copper rings on the inner electrode rod of the DBD reactor changes the local discharge gap and electric field, increases the local electric field, and makes the discharge more stable and the intensity more uniform. At the same time, it increases the charge collision probability rate and improves the SF6 degradation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0032] Figure 1 This is a test diagram of a copper-free system for the method of degrading SF6 based on placing copper rings on electrodes inside DBD according to the present invention.

[0033] Figure 2 The method for degrading SF6 based on placing copper rings on electrodes inside DBD according to the present invention has an experimental diagram of a copper ring system.

[0034] Figure 3 These are the Lissajous figures of two systems of the method for degrading SF6 based on placing copper rings on the inner electrodes of DBD according to the present invention.

[0035] Figure 4 This is a schematic diagram of the system framework for degrading SF6 based on placing copper rings on electrodes within DBD according to the present invention.

[0036] Figure 5 This is a schematic diagram of the framework of the gas supply part of the system for degrading SF6 based on placing copper rings on the electrodes inside the DBD according to the present invention.

[0037] Figure 6 This is a schematic diagram of the framework of the absorption part of the system for degrading SF6 based on placing copper rings on the electrodes inside the DBD according to the present invention.

[0038] Figure 7 This is a schematic diagram of the structure of the system adsorption component for degrading SF6 based on placing copper rings on the DBD inner electrode of the present invention. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] 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 term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0042] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0043] Example 1

[0044] A method for degrading SF6 based on placing copper rings on electrodes in a DBD includes delivering precisely proportioned and diluted SF6 to a DBD reactor 200, discharging electrode rods in the DBD reactor 200 to form an electric field, and utilizing a plurality of copper rings 201 on the electrode rods to change the local discharge gap and the electric field to complete the degradation of SF6.

[0045] Furthermore, the inner diameter of the copper ring 201 is consistent with the outer diameter of the electrode rod, and the thickness of the copper ring 201 is 1.6 mm. The gap between two adjacent copper rings 201 is 25 mm. The local discharge gap of the copper ring 201 is smaller, which increases the local electric field. The uneven discharge gap makes the discharge more stable and the intensity more uniform, while increasing the charge collision probability rate and the SF6 degradation rate.

[0046] Specifically, the setting of the copper ring 201 increases the local electric field, displacement charge and discharge fraction, and also makes the discharge more stable and the intensity more uniform, reduces the local discharge gap and changes the electric field, promotes discharge, and has little effect on the discharge volume, which can induce discharge on the copper ring 201, thereby changing the discharge distribution and making the plasma more uniform, thereby improving the plasma discharge performance of the DBD reactor 200.

[0047] Furthermore, the gas used to dilute SF6 is Ar, and the amount used is: 98% Ar dilutes 2% SF6. This ratio can ensure the dilution effect of SF6, and the diluted mixed gas has a better treatment effect in the DBD reactor 200.

[0048] Furthermore, the electrode rods in the DBD reactor 200 are powered by a plasma power supply, which uses an AC power supply, and the AC voltage provided by the plasma power supply is 10kHz of 2-4kW. A sufficiently high AC voltage is applied between the electrode rods by the plasma power supply to generate a discharge phenomenon. During the discharge process, a high-frequency, high-voltage AC electric field is formed between the inner electrode and the outer electrode, which stimulates the dielectric barrier discharge in the DBD reactor 200 and generates plasma. In the plasma environment, SF6 molecules are bombarded by high-energy electrons, ionized and excited molecules, and cracking reactions occur to generate low-toxic or non-toxic decomposition products (such as sulfur, fluoride, etc.). The generated decomposition products are easier to adsorb and process than SF6, which reduces the amount of dilution gas used, reduces cost waste, and effectively improves the degradation efficiency of SF6.

[0049] Furthermore, grounding wires are installed at both ends of the electrode rod to standardize electricity usage regulations and reduce safety hazards.

[0050] Test results:

[0051] In order to explore the changes in electrical parameters of the copper ring system placed on the inner electrode rod of the DBD reactor 200, the discharge voltage and current of the system were detected, and the Lissajous figure of the discharge was analyzed, such as Figure 1 , Figure 2 and Figure 3 As shown;

[0052] from Figure 1 and Figure 2 It can be seen that the discharge voltage and current waveforms are both sinusoidal waveforms, and the discharge system is capacitive;

[0053] There are more filament discharges caused by uneven discharge in the system without copper rings. After the copper ring system is placed, the discharge current waveform is closer to a sine waveform due to the change in the reactor capacitance. The discharge dielectric capacitance increases from 57.63pF in the empty tube system to 75.54pF, and the discharge current phase is more advanced, while the discharge current does not increase significantly. After the copper ring is placed, the discharge is more uniform.

[0054] Figure 3 The Lissajous figure of the discharge of the DBD reactor 200 before and after the copper ring is placed. The area of ​​the Lissajous figure increases significantly after filling with glass beads, indicating that more energy is used to stimulate the decomposition reaction of SF6 molecules. In addition, the amplitude of the charge transfer amount also increases, indicating that in each discharge cycle, more energy participates in the reaction. This further indicates that after placing the copper ring 201, the degradation of SF6 is greatly improved.

[0055] Example 2

[0056] Reference Figure 4-5This embodiment is different from the first embodiment in that: this embodiment discloses a system for degrading SF6 based on placing copper rings on electrodes inside DBD, which is applied to the above-mentioned method for degrading SF6 based on placing copper rings on electrodes inside DBD, and includes:

[0057] The gas supply part 100 is used to mix the Ar and SF6 mixed gas with the required concentration;

[0058] The DBD reactor 200 has a plurality of copper rings 201 equidistantly arranged on the electrode rod inside thereof, and is provided with an air inlet nozzle 202 and an air outlet nozzle 203;

[0059] The air inlet end of the absorption unit 300 is communicated with the air outlet nozzle 203 .

[0060] Furthermore, the gas supply part 100 includes:

[0061] The gas storage unit 101 is composed of two gas tanks, and the two gas tanks are used to store Ar and SF6 gas respectively;

[0062] The gas distributor 102 has a gas inlet end connected to a gas tank and a gas outlet end connected to the DBD reactor 200, and is used to transport the proportioned Ar and SF6 mixed gas to the DBD reactor 200.

[0063] Specifically, the two gas cylinders are connected to the gas distributor 102 through two gas paths, and both gas paths are equipped with rotary valves and electromagnetic flowmeters. After the gas cylinder pressure reducing valves reduce pressure, the gas enters the two gas paths at specified pressures. The electromagnetic flowmeters monitor the flow rates of the Ar gas or SF6 gas. The two gases are introduced into the gas distributor 102 and mixed in a suitable ratio to achieve accurate dilution of SF6, and the rotary valves control the opening and closing process of the Ar gas path or the SF6 gas path.

[0064] The diluted SF6 enters the DBD reactor 200, and a sufficiently high AC voltage is applied between the electrode rods through a plasma power supply to generate a discharge phenomenon. During the discharge process, a high-frequency, high-voltage AC electric field is formed between the inner electrode and the outer electrode, which stimulates the dielectric barrier discharge in the DBD reactor 200 and generates plasma. In the plasma environment, the SF6 molecules are bombarded by high-energy electrons, ionized and excited molecules, and cracking reactions occur to generate low-toxic or non-toxic decomposition products (such as sulfur, fluoride, etc.). The generated decomposition products are easier to adsorb and process than SF6, which reduces the amount of dilution gas used, reduces cost waste, and effectively improves the degradation efficiency of SF6.

[0065] Further, the absorption unit 300 includes:

[0066] The gas detector 301 is used to detect the SF6 concentration in the gas discharged from the DBD reactor 200, and detect the SF6 concentration before and after degradation to calculate its degradation rate;

[0067] The adsorption component 302 is used to degrade and absorb the gas discharged from the DBD reactor 200, and utilize the adsorption component to adsorb the generated decomposition products to achieve pollution-free SF6 treatment.

[0068] The rest of the structure is the same as that of Example 1.

[0069] Example 3

[0070] Reference Figure 6 , this embodiment is different from the above embodiment in that: the adsorption component 302 includes:

[0071] Tower body 302a;

[0072] The liquid storage tank 302b is arranged at the inner bottom of the tower body 302a;

[0073] The packing layer 302c is arranged in the middle section of the tower body 302a and is used to absorb and clean harmful gases in the rising gas;

[0074] The spray head 302d is used to spray the treatment liquid in the liquid storage tank 302b from top to bottom, so that it contacts and settles with the rising gas.

[0075] Specifically, the generated decomposition gas enters the tower body 302a and moves upward. The rising gas rises again after being adsorbed by the packing layer 302c. The packing layer 302c uses Raschig rings. The Raschig rings can provide sufficient contact surface between the gas and liquid phases to promote mass transfer and reaction between the gas and liquid. At the same time, the Raschig rings have a strong adsorption capacity due to their high specific surface area.

[0076] The spray head 302d is connected to the liquid reservoir 302b through a pipeline, and a water pump is installed on the pipeline. The water pump sucks out the treatment liquid in the liquid reservoir 302b, and the sucked treatment liquid is sprayed out through the spray head 302d. The sprayed treatment liquid forms droplets or liquid films downward, and the droplets or liquid films are in reverse contact with the upward gas. The gas is fully in contact with the treatment liquid in the tower body 302a. Through the mass transfer process on the gas-liquid interface, the pollutants in the gas are absorbed or neutralized by the treatment liquid. The gas treated by the treatment liquid passes through a demister or other gas-liquid separation device at the upper part of the tower body 302a to separate the entrained droplets. The clean gas is discharged from the top of the tower body 302a, and the treatment liquid absorbed by the pollutants falls into the liquid reservoir 302b. After treatment, it can be recycled or further treated to reduce the discharge of waste liquid and the treatment cost.

[0077] Furthermore, the treatment liquid is any one of water, alkaline solution or acid solution, which can be used specifically according to the decomposition products generated after degradation.

[0078] The rest of the structure is the same as that of Example 2.

[0079] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0080] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0081] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for degrading SF6 based on placing copper rings in DBD inner electrodes, characterized in that: The method comprises: delivering SF6 diluted in an accurately proportioned manner to a DBD reactor (200); the electrode rods in the DBD reactor (200) discharge to form an electric field; and using a plurality of copper rings (201) on the electrode rods to change the local discharge gap and the electric field to complete the degradation of SF6.

2. The method for degrading SF6 based on placing copper rings in DBD inner electrodes according to claim 1, characterized in that: The inner diameter of the copper ring (201) is consistent with the outer diameter of the electrode rod, the thickness of the copper ring (201) is 1.6 mm, and the gap between two adjacent copper rings (201) is 25 mm.

3. The method for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 2, characterized in that: The gas used to dilute SF6 is Ar, and the amount used is: 98% Ar dilutes 2% SF6.

4. The method for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 3, characterized in that: The electrode rods in the DBD reactor (200) are powered by a plasma power supply, which uses an AC power supply and provides an AC voltage of 2-4kW at 10kHz.

5. The method for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 4, characterized in that: Both ends of the electrode rod are equipped with grounding wires.

6. A system for degrading SF6 based on placing copper rings in DBD inner electrodes, characterized by: The method for degrading SF6 based on placing copper rings in DBD inner electrodes as described in claim 1 comprises: The gas supply part (100) is used to mix Ar and SF6 mixed gas with the required concentration; A DBD reactor (200) has a plurality of copper rings (201) equidistantly arranged on an electrode rod inside the reactor, and is provided with an air inlet nozzle (202) and an air outlet nozzle (203); The air inlet end of the absorption unit (300) is connected to the air outlet nozzle (203).

7. The system for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 6, characterized in that: The gas supply part (100) comprises: A gas storage unit (101), composed of two gas tanks, the two gas tanks are used to store Ar and SF6 gas respectively; The gas distributor (102) has a gas inlet end connected to a gas tank and a gas outlet end connected to a DBD reactor (200), and is used to transport a proportioned Ar and SF6 mixed gas to the DBD reactor (200).

8. The system for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 7, characterized in that: The absorption unit (300) comprises: A gas detector (301) for detecting the concentration of SF6 in the gas exhausted from the DBD reactor (200); The adsorption assembly (302) is used to perform degradation and absorption treatment on the gas discharged from the DBD reactor (200).

9. The system for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 8, characterized in that: The adsorption component (302) comprises: Tower body (302a); A liquid storage tank (302b) is arranged at the inner bottom of the tower body (302a); The packing layer (302c) is arranged in the middle section of the tower body (302a) and is used for adsorbing and cleaning harmful gases in the ascending gas; The spray head (302d) is used to spray the treatment liquid in the liquid storage tank (302b) from top to bottom, so that it contacts and settles with the rising gas.

10. The system for degrading SF6 based on placing copper rings in DBD inner electrodes as claimed in claim 9, characterized in that: The treatment liquid is any one of water, alkaline solution or acid solution.

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