Sulfur hexafluoride degradation system

Abstract

The sulfur hexafluoride degradation system comprises a sealing box, a plasma generation device, a reaction device and a waste gas treatment device, the plasma generation device comprises a plasma generator, the output end of the plasma generator is communicated with the reaction device, the plasma generator and the reaction device are arranged in the sealing box, and the waste treatment device is used for receiving waste gas output by the reaction device; the plasma generator comprises a plasma generator body, a cathode, an anode and an arc striking device. The device has the advantages that sulfur hexafluoride is directly introduced into the plasma area, the retention time of the sulfur hexafluoride in the plasma discharge area is prolonged, sulfur hexafluoride degradation is more sufficient, the plasma characteristics are fully utilized, working medium gas entering in a rotational flow mode through the first gas path and the third gas path can restrain mixed gas and electric arcs input by the second gas path, and therefore sulfur hexafluoride degradation efficiency is improved. The mixed gas does not contact with the electrode to protect the surface of the electrode, and corrosion of degradation products to the electrode is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of gas degradation, in particular to a sulfur hexafluoride degradation system. Background Art

[0002] Sulfur hexafluoride (SF6) is a synthetic gas. Due to its excellent electrical properties and arc extinguishing performance, it is widely used in gas-insulated switchgear, gas-insulated transformers (GIT), gas-insulated lines (GIL) and gas-insulated circuit breakers (GCB), etc., and has become an important part of the high voltage and ultra-high voltage fields of the power system. With the continuous development of the power industry, the number of SF6 electrical equipment has gradually increased. Most of the world's SF6 is used in high-voltage electrical equipment in the form of pure gas or mixed gas (such as SF6 / N2). At present, how to achieve efficient and environmentally friendly disposal of existing SF6 gas has become a major technical problem facing the power industry.

[0003] SF6 molecules are octahedral in configuration, extremely stable in nature, and difficult to degrade naturally. There is a serious lack of commercial equipment for SF6 degradation in the power industry, and only high-temperature thermal degradation is used. On the one hand, since SF6 waste gas in the power grid is still mainly recycled, stored or reused, there are no clear waste gas treatment standards and specifications, and there is a lack of effective guidance; on the other hand, the existing degradation technology is mainly aimed at the needs of the semiconductor and metal processing fields, most of which have the characteristics of low concentration and small volume, and the treatment equipment is often integrated at the end of the processing equipment. This is significantly different from the diversified degradation needs of SF6 waste gas of different equipment types, fault types and mixed gas types in the power industry. As a result, the degradation technology other than traditional thermal degradation has not yet been effectively applied in the power industry. Therefore, it is of great significance to conduct in-depth research on the SF6 degradation process, develop SF6 efficient and harmless degradation technology, and develop distributed miniaturized equipment to achieve rapid and effective degradation of SF6 gas.

[0004] Thermal plasma has high temperature, high enthalpy and high chemical activity, and is one of the potential ways to degrade SF6 on a large scale. At present, the research on thermal plasma in SF6 degradation is mainly concentrated in the fields of semiconductor and metal processing. The SF6 concentration and volume are usually treated, which not only affects the degradation efficiency, but also wastes a lot of energy for heating the working gas. At the same time, the existing Chinese invention patent document with publication number CN115554823A discloses a sulfur hexafluoride degradation system based on thermal plasma. The device only uses plasma as a heat source to degrade SF6. Since it cannot solve the electrode corrosion caused by SF6 passing through the plasma area, the highly reactive particles in the plasma are not effectively utilized. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to prevent degradation products from corroding the electrodes of a plasma generator and to fully utilize the characteristics of plasma.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A sulfur hexafluoride degradation system, comprising a sealed box, a plasma generating device, a reaction device, and an exhaust gas treatment device;

[0008] The plasma generating device comprises a plasma generator, the output end of the plasma generator is connected to the reaction device, the plasma generator and the reaction device are arranged inside the sealed box, and the waste treatment device is used to receive the waste gas output by the reaction device;

[0009] The plasma generator comprises a plasma generator body, a cathode, an anode and an arc striking device. The output end of the plasma generator body is communicated with a reaction device. A cathode and an anode are arranged inside the plasma generator body. The arc striking device is used to generate an arc between the cathode and the anode. A first gas path for inputting a working medium gas is arranged on the cathode. A second gas path and a third gas path are arranged on the anode. The second gas path arranged between the first gas path and the third gas path is used to input sulfur hexafluoride gas. The third gas path is used to input a working medium gas. The output directions of the first gas path, the second gas path and the third gas path are all arranged toward the output end of the plasma generator.

[0010] Since the second gas path is arranged between the first gas path and the third gas path, sulfur hexafluoride is introduced from between the anode and the cathode in the plasma generator, and sulfur hexafluoride is directly introduced into the plasma area, so that its residence time in the plasma discharge area becomes longer, sulfur hexafluoride is more fully degraded, and the plasma characteristics can be fully utilized to improve the sulfur hexafluoride treatment concentration, treatment volume and degradation rate. In addition, since the output directions of the first gas path, the second gas path and the third gas path are all arranged toward the output end of the plasma generator, the working gas swirled into the first gas path and the third gas path of the plasma generator can constrain the mixed gas and the arc input by the second gas path, so that the mixed gas will not contact the electrode to protect the electrode surface, and avoid the degradation products from corroding the plasma generator electrode.

[0011] Preferably, the plasma generating device further includes a power supply unit, a gas supply unit, and a cooling protection unit, wherein the power supply unit is electrically connected to the cathode, the anode and the arc striking device, the gas supply unit is used to supply gas to the first gas path, the second gas path and the third gas path, and the cooling unit is used to cool the anode.

[0012] Preferably, the gas supply unit comprises a first gas tank, a second gas tank and a gas mixing tank, the output end of the first gas tank is connected to the input of the gas mixing tank, the output end of the second gas tank is respectively connected to the gas mixing tank, the first gas path and the third gas path, and the output end of the gas mixing tank is connected to the second gas path.

[0013] Preferably, the negative electrode and the positive electrode of the power supply unit are respectively connected to the anode and the cathode of the plasma generator, and the arc striking device generates a high voltage for arc striking, and provides a constant current between the anode and the cathode after the arc is generated.

[0014] Preferably, the reaction device includes a reactor, a spray structure and a heat exchange structure. The reactor is arranged in a sealed box, the output end of the plasma generator is connected to the gas input end of the reactor, the gas output end of the reactor is connected to the exhaust gas treatment device, a spray structure and an alkali solution are arranged in the reactor, the input end of the spray structure is connected to the alkali solution in the reactor, and the input end of the spray structure is also provided with a heat exchange structure.

[0015] Preferably, the spray structure includes a spray head, a spray pipe and a pneumatic diaphragm pump. Spray heads are correspondingly arranged at the gas input end and the output end of the reactor. The spray head is connected to the alkaline solution in the reactor through the spray pipe. The pneumatic diaphragm pump and the heat exchange structure are arranged on the spray pipe.

[0016] Preferably, the exhaust gas treatment device comprises a 13X molecular sieve chamber and an activated alumina chamber which are sequentially arranged along the flow direction of the gas path.

[0017] Preferably, the exhaust gas treatment device further comprises a chromatograph and a spectrometer for detecting the gas exhausted from the reactor.

[0018] Preferably, the working gas is air, nitrogen or hydrogen.

[0019] Preferably, the gas flow rate in the second gas path is 5Nm 3 / hr.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Since the second gas path is arranged between the first gas path and the third gas path, sulfur hexafluoride is introduced between the anode and the cathode of the plasma generator, and sulfur hexafluoride is directly introduced into the plasma area, so that its residence time in the plasma discharge area becomes longer, and sulfur hexafluoride is more fully degraded, and the plasma characteristics can be fully utilized to improve the sulfur hexafluoride treatment concentration, treatment volume and degradation rate. And since the output directions of the first gas path, the second gas path and the third gas path are all arranged toward the output end of the plasma generator, the working gas swirled into the first gas path and the third gas path of the plasma generator can constrain the mixed gas and arc input by the second gas path, so that the mixed gas will not contact the electrode to protect the electrode surface, and avoid the corrosion of the degradation products to the plasma generator electrode.

[0022] 2. The degradation system has the advantages of no need for catalysts, high rate, and high throughput, and is expected to achieve efficient and large-scale degradation of sulfur hexafluoride waste gas, with direct economic and environmental protection benefits. Compared with other existing sulfur hexafluoride degradation technologies, the present invention has a high threshold for the concentration of sulfur hexafluoride waste gas that can be degraded and a fast degradation rate, which can significantly reduce the unit gas treatment cost and improve economic efficiency; more efficient use of energy, reducing energy waste in heating working gas; and quickly achieving harmless treatment of sulfur hexafluoride waste gas from faulty equipment and waste gas from small gas chambers at substation sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the structure of a plasma generator according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] To facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings.

[0026] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] In this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically limited.

[0028] See also Figure 1 to Figure 2 , this embodiment discloses a sulfur hexafluoride degradation system, including a sealed box 1, a plasma generating device, a reaction device 2, and an exhaust gas treatment device 3;

[0029] The plasma generating device comprises a plasma generator 4, a power supply unit, a gas supply unit 5, and a cooling protection unit 6. The plasma generator 4 comprises a plasma generator body (not marked in the figure), a cathode 41, an anode 42, and an arc striking device (not shown in the figure). The output end of the plasma generator body is connected to the reaction device 2. The plasma generator body and the reaction device 2 are both arranged inside the sealed box 1. A cathode 41 and an anode 42 are arranged inside the plasma generator body. The arc striking device is used to generate an arc 42 between the cathode 41 and the anode 42. The power supply unit is electrically connected to the cathode 41, the anode 42, and the arc striking device. Specifically, the negative electrode and the positive electrode of the power supply unit are respectively connected to the cathode 41 and the cathode 42 of the plasma generator. The arc striking device generates a high voltage for arc striking, and provides a constant current between the cathode 41 and the cathode 42 after the arc is generated.

[0030] Furthermore, the power supply unit is a plasma power supply, and its operating voltage is 200V and the operating current is 100A.

[0031] The cathode 42 is provided with a first gas path 421 for inputting a working gas, the cathode 41 is provided with a second gas path 411 and a third gas path 412, the second gas path 411 is arranged between the first gas path 421 and the third gas path 412, and the output directions of the first gas path 421, the second gas path 411 and the third gas path 412 are all arranged toward the output end of the plasma generator 4.

[0032] The gas supply unit 5 includes a first gas tank 51, a second gas tank 52 and a gas mixing tank 53. The output end of the first gas tank 51 is connected to the input end of the gas mixing tank 53. The output end of the second gas tank 52 is respectively connected to the gas mixing tank 53, the first gas path 421 and the third gas path 412. The output end of the gas mixing tank 53 is connected to the second gas path 411. The first gas tank 51 contains sulfur hexafluoride gas, and the second gas tank 52 contains working fluid gas. In this embodiment, the working fluid gas is air, nitrogen or hydrogen.

[0033] Furthermore, the gas flow rate in the second gas path 411 is 5 Nm 3 / hr, of which the sulfur hexafluoride gas flow rate is 0.5Nm 3 / hr, working gas flow rate is 4.5Nm 3 / hr.

[0034] The cooling unit 6 is used to cool the anode 42 . A cooling channel is provided on the anode 42 . The cooling unit 6 is connected to the cooling channel. The cooling liquid input through the cooling unit 6 cools the anode 42 .

[0035] The reaction device 2 includes a reactor 21, a spray structure 22 and a heat exchange structure 23. The reactor 21 is arranged in a sealed box 1. The output end of the plasma generator 4 is connected to the gas input end of the reactor 21. The high-temperature plasma generated in the plasma generator 4 and the gas that has not formed high-temperature plasma are input into the reactor 21. The gas output end of the reactor 21 is connected to the exhaust gas treatment device 3. The reactor 21 is provided with a spray structure 22 and an alkali solution. The input end of the spray structure 22 is connected to the alkali solution in the reactor 21. The input end of the spray structure 23 is also provided with a heat exchange structure 23.

[0036] The spray structure 23 includes a spray head 231, a spray pipe 232 and a pneumatic diaphragm pump 233. The spray head 231 is correspondingly arranged at the gas input end and the output end of the reactor 21. The spray head 231 is connected with the alkali solution in the reactor 21 through the spray pipe 232. The pneumatic diaphragm pump 233 and the heat exchange structure 23 are arranged on the spray pipe 232. Specifically, the alkali solution in the reactor 21 is driven to circulate by the pneumatic diaphragm pump 233, and the gas input end and the output end of the reactor 21 are sprayed by the spray head 231, wherein the gas input end of the reactor 21 is sprayed to absorb the acidic gas generated in the plasma generator 4 through the alkali solution, and the gas output end of the reactor 21 is sprayed to further spray the output waste gas through the alkali solution to further absorb the acidic gas therein; wherein the power of the pneumatic diaphragm pump 233 comes from the air compressor.

[0037] Furthermore, the heat exchange structure 23 is a heat exchanger.

[0038] The waste treatment device 3 is used to receive the waste gas output by the reaction device; specifically, the waste gas treatment device 7 includes a 13X molecular sieve chamber, an activated alumina chamber, a chromatograph and a spectrometer arranged in sequence along the flow direction of the gas path. The waste gas is absorbed by the 13X molecular sieve chamber and the activated alumina chamber, and the chromatograph and the spectrometer are used to detect whether the gas discharged from the reactor meets the standards.

[0039] Furthermore, to ensure safety, the sealed box 1 is kept in a vacuum state by a vacuum pump, and a sulfur hexafluoride detector is provided on the sealed box 1 to detect the sulfur hexafluoride in the sealed box 1 to prevent the sulfur hexafluoride from leaking out.

[0040] Specifically, the working gas may be nitrogen, hydrogen, air and other gases. The reaction product of N in the working gas will generate NF3, which is a greenhouse gas; the reaction product of H in the working gas will generate HF, which is easy to absorb by alkali solution; the reaction product of O in the working gas will generate SO2F2, SOF2, SOF4, SO2 and other compounds; the reaction product of C in the working gas will generate CF4, which is a greenhouse gas.

[0041] Taking air as the working gas as an example, the main products after sulfur hexafluoride degradation include HF, SO2F2, SOF2, and trace amounts of greenhouse gases such as NF3 and CF4 are also generated. The above gases can be completely absorbed by alkali solution, 13X molecular sieve and activated alumina.

[0042] More preferably, the proportion of sulfur hexafluoride can be reduced to 1%, which can further improve the treatment efficiency of sulfur hexafluoride.

[0043] More preferably, the proportion of sulfur hexafluoride can be further increased to 20%, which can further improve the sulfur hexafluoride treatment capacity.

[0044] The working principle of this embodiment is:

[0045] First, the cooling protection unit 6 is turned on to drive the cooling water to cool the plasma generator 4 through the cooling water inlet line and the cooling water outlet line, and then the first gas tank 51 and the second gas tank 52 are turned on to input the working gas and the sulfur hexafluoride gas into the mixing tank 53, and the working gas is introduced into the first gas path 421 and the third gas path 412 in the plasma generator 4. After the flow rate is set, the plasma power supply and the arc striking device are used to strike the arc to generate a thermal arc plasma, and then the mixed gas obtained by mixing the working gas in the mixing tank 53 with the sulfur hexafluoride gas is introduced into the second gas path 421 and the third gas path 412 of the plasma generator 4. 411, since sulfur hexafluoride is introduced between the anode and the cathode in the plasma generator 4, its residence time in the plasma discharge area becomes longer, and the sulfur hexafluoride is degraded more fully, and since the output directions of the first gas path 421, the second gas path 411 and the third gas path 412 are all arranged toward the output end of the plasma generator 4, the working gas swirled into the first gas path 421 and the third gas path 412 of the plasma generator 2 can constrain the mixed gas and the arc input from the second gas path 411, so that the mixed gas will not contact the electrode to protect the electrode surface and prevent electrode corrosion.

[0046] Then, the acidic gas generated by the plasma generator 4 is absorbed by the alkali solution sprayed by the spray head 231. The alkali solution is driven to circulate by the pneumatic diaphragm pump 233. The alkali solution is cooled by the heat exchange structure 23. The cooling capacity of the heat exchange structure 23 is provided by the circulating water cooler arranged outside the sealed box 1. The gas not absorbed by the alkali solution is led to the waste gas treatment device 7. The waste gas is absorbed by the 13X molecular sieve chamber and the activated alumina chamber. The gas discharged from the reactor is tested by a chromatographic analyzer and a spectrometer to determine whether it meets the standards. The waste gas finally obtained can be extracted and discharged by a vacuum pump after being tested to meet the standards.

[0047] In summary, in the present invention, since the second gas path 411 is arranged between the first gas path 421 and the third gas path 412, sulfur hexafluoride is introduced from between the cathode 41 and the cathode 42 in the plasma generator 4, and sulfur hexafluoride is directly introduced into the plasma region, and its residence time in the plasma discharge region becomes longer, and sulfur hexafluoride is more fully degraded, and the plasma characteristics can be fully utilized to improve the sulfur hexafluoride treatment concentration, treatment amount and degradation rate. And since the output directions of the first gas path 421, the second gas path 411 and the third gas path 412 are all arranged toward the output end of the plasma generator 4, the working fluid gas swirled into the first gas path 421 and the third gas path 412 of the plasma generator 2 can constrain the mixed gas and arc input from the second gas path 411, so that the mixed gas will not contact the electrode to protect the electrode surface, and avoid the degradation product from corroding the electrode of the plasma generator 4.

[0048] In addition, the degradation system has the advantages of no need for catalysts, high rate, and high throughput, and is expected to achieve efficient and large-scale degradation of sulfur hexafluoride waste gas, with direct economic and environmental protection benefits. Compared with other existing sulfur hexafluoride degradation technologies, the present invention has a high threshold for the concentration of sulfur hexafluoride waste gas that can be degraded and a fast degradation rate, which can significantly reduce the unit gas treatment cost and improve economic efficiency; more efficient use of energy, reducing energy waste in heating working gas; and quickly achieving harmless treatment of sulfur hexafluoride waste gas from faulty equipment and waste gas from small gas chambers at substation sites.

[0049] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0050] The above-described embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A sulfur hexafluoride degradation system, characterized in that: It includes a sealed box, a plasma generating device, a reaction device, and an exhaust gas treatment device; The plasma generating device comprises a plasma generator, the output end of the plasma generator is connected to the reaction device, the plasma generator and the reaction device are arranged inside the sealed box, and the waste treatment device is used to receive the waste gas output by the reaction device; The plasma generator comprises a plasma generator body, a cathode, an anode and an arc striking device. The output end of the plasma generator body is communicated with a reaction device. A cathode and an anode are arranged inside the plasma generator body. The arc striking device is used to generate an arc between the cathode and the anode. A first gas path for inputting a working medium gas is arranged on the cathode. A second gas path and a third gas path are arranged on the anode. The second gas path arranged between the first gas path and the third gas path is used to input sulfur hexafluoride gas. The third gas path is used to input a working medium gas. The output directions of the first gas path, the second gas path and the third gas path are all arranged toward the output end of the plasma generator.

2. A sulfur hexafluoride degradation system according to claim 1, characterized in that: The plasma generating device further comprises a power supply unit, a gas supply unit and a cooling protection unit. The power supply unit is electrically connected to the cathode, the anode and the arc striking device. The gas supply unit is used to supply gas to the first gas path, the second gas path and the third gas path. The cooling unit is used to cool the anode.

3. A sulfur hexafluoride degradation system according to claim 2, characterized in that: The gas supply unit includes a first gas tank, a second gas tank and a gas mixing tank. The output end of the first gas tank is connected to the input of the gas mixing tank. The output end of the second gas tank is respectively connected to the gas mixing tank, the first gas path and the third gas path. The output end of the gas mixing tank is connected to the second gas path.

4. A sulfur hexafluoride degradation system according to claim 2, characterized in that: The negative electrode and the positive electrode of the power supply unit are connected to the anode and the cathode of the plasma generator respectively. The arc striking device generates a high voltage for arc striking, and provides a constant current between the anode and the cathode after the arc is generated.

5. A sulfur hexafluoride degradation system according to claim 1, characterized in that: The reaction device includes a reactor, a spray structure and a heat exchange structure. The reactor is arranged in a sealed box. The output end of the plasma generator is connected to the gas input end of the reactor. The gas output end of the reactor is connected to the exhaust gas treatment device. A spray structure and alkali solution are arranged in the reactor. The input end of the spray structure is connected to the alkali solution in the reactor. The input end of the spray structure is also provided with a heat exchange structure.

6. A sulfur hexafluoride degradation system according to claim 5, characterized in that: The spray structure includes a spray head, a spray pipe and a pneumatic diaphragm pump. Spray heads are correspondingly arranged at the gas input end and the output end of the reactor. The spray head is connected to the alkaline solution in the reactor through the spray pipe. The pneumatic diaphragm pump and the heat exchange structure are arranged on the spray pipe.

7. A sulfur hexafluoride degradation system according to claim 1, characterized in that: The exhaust gas treatment device comprises a 13X molecular sieve chamber and an activated alumina chamber which are sequentially arranged along the flow direction of the gas path.

8. A sulfur hexafluoride degradation system according to claim 7, characterized in that: The exhaust gas treatment device also includes a chromatograph and a spectrum analyzer for detecting the gas exhausted from the reactor.

9. A sulfur hexafluoride degradation system according to claim 1, characterized in that: The working gas is air, nitrogen or hydrogen.

10. A sulfur hexafluoride degradation system according to claim 1, characterized in that: The gas flow rate in the second gas path is 5Nm 3 / hr.

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