Sulfur hexafluoride recycling and degrading combined process for high-voltage insulation equipment

Abstract

The invention discloses a sulfur hexafluoride recovery and degradation combined process for high-voltage insulation equipment, and relates to the technical field of sulfur hexafluoride recovery, and the sulfur hexafluoride recovery and degradation combined process comprises the following steps: (1) primarily recovering sulfur hexafluoride gas in a cavity of the high-voltage insulation equipment; (2) after the preliminary recovery is completed, filling air into the equipment cavity; (3) extracting the residual mixed gas of sulfur hexafluoride gas and air in the cavity, and degrading; (4) repeating the step (2) and the step (3) for one or more times, and opening the equipment for maintenance; the device breaks the situation that the lower the pressure is in the recovery process, the longer the recovery and air exhaust time is; and through a one-time or multi-time gas replacement mode, residual gas after recovery in the cavity is taken out as much as possible and degraded within limited time until emission reduction and harmlessness are achieved.

Description

Technical Field

[0001] This invention relates to the field of sulfur hexafluoride recovery technology, specifically to a combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment. Technical Background

[0002] Sulfur hexafluoride (SF6) is a synthetic gas. It has an octahedral molecular configuration, with a sulfur atom at the center surrounded by six fluorine atoms, and the entire molecule surface is enveloped by an electron cloud. The global warming potential (GWP) of sulfur hexafluoride is approximately 23,500 times that of the same amount of carbon dioxide (CO2) over a 100-year period. Its unique molecular structure gives SF6 excellent stability, electrical insulation, and arc-quenching properties, making it widely used in various high-voltage insulation equipment for insulating high-voltage switchgear. Reducing SF6 emissions, especially during routine maintenance of high-voltage insulation equipment, is of paramount importance.

[0003] According to Section 5.1.2 of Part 1 of the People's Republic of China Electric Power Industry Standard DL / T 662.1-2021 "Technical Conditions for Sulfur Hexafluoride Gas Recovery Devices": the termination pressure for gas recovery in the gas chamber is 1.33 × 10⁻⁶. -3 MPa. Existing sulfur hexafluoride gas recovery processes for high-voltage insulation equipment, such as... Figure 1 As shown: (1) Positive pressure recovery: The sulfur hexafluoride gas in the cavity of the high-voltage insulation equipment was recovered from an initial pressure of ≤0.8MPa to 0.1MPa.

[0004] (2) Negative pressure recovery: When the residual pressure in the high-voltage insulation equipment cavity reaches 0.1 MPa, it continues to be recovered to 1.33 × 10⁻⁶ MPa. -3 MPa (1.33 kPa).

[0005] (3) Equipment maintenance Inject air to 0.1 MPa and perform equipment maintenance.

[0006] After the recovery is completed and the vacuum is broken, the chamber can be opened for maintenance. At this point, a maximum concentration of 13,300 ppm will remain per cubic meter of chamber. The residual sulfur hexafluoride will be discharged through forced ventilation. For example... Figure 2 As shown: With the existing recovery process, without considering factors such as pressure rebound within the cavity and gas adhesion to the cavity wall, the recovery time is approximately 145 minutes.

[0007] Because existing sulfur hexafluoride (SF6) gas recovery processes for high-voltage insulation equipment suffer from long recovery times and high SF6 concentrations after recovery, a combined SF6 recovery and degradation technology suitable for high-voltage insulation equipment needs to be designed to reduce SF6 greenhouse gas emissions from the power industry and ensure environmental health during maintenance and upkeep. Summary of the Invention

[0008] To reduce sulfur hexafluoride (SF6) greenhouse gas emissions from the power industry and ensure environmental health during maintenance and operation, this invention provides a combined process for SF6 recovery and degradation in high-voltage insulation equipment. This process achieves efficient recovery and degradation of residual SF6 gas in the equipment on-site without extending (reducing) actual working time.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following solution: A combined process for the recovery and degradation of sulfur hexafluoride in high-voltage insulation equipment includes the following steps: (1) Preliminary recovery of sulfur hexafluoride gas in the cavity of high-voltage insulation equipment; (2) After the initial recovery is completed, air is introduced into the equipment cavity; (3) Extract the mixture of residual sulfur hexafluoride gas and air from the cavity and degrade it; (4) After repeating steps (2) and (3) once or more, open the equipment for maintenance.

[0010] Further settings are as follows: In step (1): The initial pressure in the cavity of the high-voltage insulation equipment is ≤0.8 MPa.

[0011] The initial recovery involves extracting sulfur hexafluoride gas from the high-voltage insulation equipment cavity until the cavity pressure reaches 0.01 MPa. More specifically: the sulfur hexafluoride gas in the high-voltage insulation equipment cavity is first recovered from an initial pressure ≤0.8 MPa to 0.1 MPa, and when the residual pressure in the high-voltage insulation equipment cavity reaches 0.1 MPa, recovery continues to 0.01 MPa (10 kPa).

[0012] In step (2): After the initial recovery is completed, air is introduced into the equipment cavity until the cavity pressure reaches 0.1 MPa.

[0013] In step (3): Extract the residual sulfur hexafluoride gas and air mixture from the chamber until the chamber pressure is 0.01–0.05 MPa.

[0014] In step (3): The degradation can be any one of plasma degradation, thermocatalytic degradation, or photocatalytic degradation, preferably thermocatalytic degradation.

[0015] The thermocatalytic degradation process conditions are as follows: the degradation temperature is 600℃, and the degradation catalyst is a manganese-based catalytic material.

[0016] The preparation method of the manganese-based catalytic material is as follows: using manganese metal as the active site center, silicon carbide as the support for manganese metal, controlling the mass ratio of support to manganese metal to be 4:1, mixing manganese metal and silicon carbide, and then grinding to obtain powdered manganese-based catalytic material.

[0017] The present invention also provides a sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment, characterized in that it includes a main recovery circuit and a degradation branch circuit. The main recovery circuit includes a recovery interface, a recovery pump, a buffer tank, a compressor, a filter and a gas storage interface connected in sequence through pipelines. The degradation branch circuit includes a thermal degradation tower, a heat exchanger, an acid-base neutralization tower and a tail gas measuring chamber connected in sequence through pipelines.

[0018] Further settings are as follows: The recycling interface is used to connect to the exhaust port of the high-voltage insulation equipment to which sulfur hexafluoride is to be recycled, and the recycling pump is a gas-powered system for recycling and degradation.

[0019] A first pressure controller and a first vent valve are connected on the pipeline between the recovery interface and the recovery pump. The first pressure controller and the first vent valve are used to control the gas pressure at the recovery interface or in the cavity to be recovered sulfur hexafluoride, and to fill the cavity with gas under vacuum or negative pressure.

[0020] The buffer tank is used to store the gas recovered from the recovery pump. A second vent valve and a buffer tank valve are installed between the buffer tank and the recovery pump, and a second pressure controller is connected to the buffer tank.

[0021] The gas coming out of the buffer tank is partly compressed by the compressor and sent to the gas storage interface, and partly sent to the degradation branch, where it is discharged after degradation.

[0022] The compressor is connected to the buffer tank. The compressor is used to further compress the gas coming out of the buffer tank. After compression, the gas is filtered and then stored in the gas storage device through the gas storage interface.

[0023] The compressor is an oil-free scroll pump or an oil-free screw pump.

[0024] A filter is connected to the rear end of the compressor, and an air storage valve is installed between the compressor and the filter.

[0025] The gas storage interface is connected to the filter. The filtered gas is stored in the gas storage device through the gas storage interface. A third pressure controller is installed at the gas storage interface.

[0026] The thermal degradation tower is connected to the buffer tank via a degradation valve. The thermal degradation tower is used for the thermal catalytic degradation of sulfur hexafluoride gas. A gas flow meter is installed between the degradation valve and the thermal degradation tower.

[0027] The heat exchanger is connected to the thermal degradation tower and is used for heat exchange between the inlet air and the outlet air of the thermal degradation tower.

[0028] The gas, after being degraded in the thermal degradation tower, enters the acid-base neutralization tower. After acid-base neutralization treatment, the exhaust gas is tested by the exhaust gas measurement chamber. Once it meets environmental protection requirements, it is discharged.

[0029] The present invention provides a sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment, comprising independent recovery and combined recovery and degradation functions: (1) Independent recycling Gas recovery path: The gas passes sequentially through the recovery interface, recovery pump, buffer tank valve, buffer tank, compressor, gas storage valve, filter, and gas storage interface, and is then pressurized into the gas storage device; When using the independent recovery function, the high-voltage insulation equipment for recovering sulfur hexafluoride gas is connected to the sulfur hexafluoride recovery and degradation device of the present invention through the corresponding interface. The first pressure controller reads the pressure inside the high-voltage insulation equipment cavity and sequentially opens the buffer tank valve, recovery pump, compressor, and gas storage valve, closes the degradation valve, and pressurizes the recovered gas into the gas storage device through the gas storage interface. (2) Combined recycling and degradation The combined recycling and degradation function includes two parts: recycling the gas in the cavity and filling the cavity with air—degrading the gas in the cavity by evacuating it. Gas recovery path: The gas passes sequentially through the recovery interface, recovery pump, buffer tank valve, buffer tank, compressor, gas storage valve, filter, and gas storage interface, and is then pressurized into the gas storage device; Gas degradation path: The gas passes sequentially through the recovery interface, recovery pump, buffer tank valve, buffer tank, degradation valve, gas flow meter, thermal degradation tower, heat exchanger, acid-base neutralization tower, and tail gas measurement chamber before being discharged; The function and control of gas recovery within the chamber remain unchanged. Simultaneously with gas recovery, the heating function of the thermal degradation tower is activated, and the temperature rises to the set temperature after the degradation operation begins. After the recovery operation is completed, the first pressure controller reads the pressure within the high-voltage insulation equipment chamber after the recovery is completed and has stabilized for a period of time. Upon reading this pressure, the first vent valve is opened to fill the chamber with air. After filling, the chamber contains a mixture of air and residual sulfur hexafluoride. Once the thermal degradation tower reaches the set temperature, the gas storage valve is closed, and the degradation valve, recovery pump, and buffer tank valve are opened. The gas sequentially passes through the recovery interface, recovery pump, buffer tank valve, buffer tank, degradation valve, gas flow meter, heat exchanger, thermal degradation tower, heat exchanger, acid-base neutralization tower, and tail gas measurement chamber. When the first pressure controller reads the set pressure, the recovery and degradation function is complete.

[0030] By repeatedly filling the cavity with air and then evacuating and degrading the gas inside the cavity, near-zero emissions of sulfur hexafluoride can be achieved.

[0031] The beneficial effects of this invention are as follows: This invention provides a combined process for the recovery and degradation of sulfur hexafluoride (SF6) in high-voltage insulation equipment. Building upon existing recovery methods used during the maintenance of electrical insulation equipment, this invention adds the degradation of residual gas after recovery, forming a combined SF6 recovery and degradation technology. This invention overcomes the limitation that lower pressures in the recovery process require longer extraction times; through one or more gas replacements, residual gas within the chamber is extracted and degraded as much as possible within a limited time, ultimately achieving emission reduction and harmlessness. Attached Figure Description

[0032] Figure 1 This is a flow chart of the sulfur hexafluoride gas recovery process for existing high-voltage insulation equipment.

[0033] Figure 2 This is a graph showing the relationship between recovery time and pressure in existing recycling processes.

[0034] Figure 3 This is a process flow diagram of the combined process of sulfur hexafluoride recovery and degradation in the high-voltage insulation equipment of the present invention.

[0035] Figure 4 This is a schematic diagram of the sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment of the present invention.

[0036] Figure 5 This is a control principle diagram of the sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment of the present invention.

[0037] Figure 6 This is the experimental design diagram for the combined recovery and degradation of sulfur hexafluoride in the simulation of high-voltage insulation equipment according to the present invention.

[0038] Figure 7 This is a graph showing the relationship between recovery degradation time and pressure based on a sulfur hexafluoride emission rate of 1%.

[0039] Figure 8 This is a diagram showing the degradation effect of the thermocatalytic degradation method used in this invention.

[0040] Figure 9 This is a graph showing the relationship between recovery degradation time and pressure based on a treatment time of 145 minutes, according to the present invention.

[0041] Figure 10 This is a graph showing the relationship between the recycling degradation time and pressure under near-zero emission conditions of this invention.

[0042] Figure 11 This is a graph showing the relationship between the recovery degradation time and pressure at a final degradation pressure of 30 kPa, as presented in this invention. Detailed Implementation

[0043] The features and techniques of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the experimental equipment and materials used in the following embodiments can be obtained commercially.

[0044] In the following examples: 0.1-0.8 MPa is positive pressure, and below 0.1 MPa is negative pressure.

[0045] like Figure 3 As shown, the present invention provides a combined process for the recovery and degradation of sulfur hexafluoride in high-voltage insulation equipment, comprising the following steps: (1) Positive pressure recovery: The sulfur hexafluoride gas in the cavity of the high-voltage insulation equipment is recovered from an initial pressure of ≤0.8MPa to 0.1MPa.

[0046] (2) Negative pressure recovery: When the residual pressure inside the high-voltage insulation equipment reaches 0.1 MPa, it is further reduced to 0.01 MPa (10 kPa).

[0047] (3) Inflate with gas: Air is introduced into the cavity of the high-voltage insulation equipment to bring the cavity pressure to 0.1 MPa (corresponding to a sulfur hexafluoride gas concentration of 10% in the equipment cavity).

[0048] (4) Extraction and degradation The mixture of sulfur hexafluoride gas and air in the cavity is extracted using a pump set and then degraded until the cavity pressure reaches 0.01 MPa.

[0049] (5) Open the cover for inspection After repeating steps (3) and (4) several times, open the equipment for maintenance.

[0050] like Figure 4 As shown, the present invention provides a sulfur hexafluoride gas recovery device for high-voltage insulation equipment, comprising a main recovery circuit and a degradation branch circuit.

[0051] The main recovery pipeline includes a recovery interface 1, a recovery pump 4, a buffer tank 7, a compressor 9, a filter 11, and a gas storage interface 13, which are connected sequentially via pipelines. The recycling interface 1 is used to connect to the exhaust port of the high-voltage insulation equipment from which sulfur hexafluoride is to be recycled.

[0052] The recovery pump 4 is used for the gas power system of recovery and degradation, and preferably uses DILO's sulfur hexafluoride gas recovery pump set B095R10+B093R10 for recovery and degradation.

[0053] A first pressure controller 2 and a first vent valve 3 are connected on the pipeline between the recovery interface 1 and the recovery pump 4. The first pressure controller 2 and the first vent valve 3 are used to control the gas pressure at the recovery interface or in the cavity to be recovered sulfur hexafluoride, and to fill the cavity under vacuum or negative pressure conditions with gas.

[0054] Buffer tank 7 is used to store the gas recovered from recovery pump 4. A second vent valve 5 and a buffer tank valve 6 are installed between buffer tank 7 and recovery pump 4, and a second pressure controller 8 is connected to buffer tank 7. The second vent valve 5 is used to perform internal vacuum treatment on the sulfur hexafluoride recovery and degradation device of the present invention, and the second pressure controller 8 is used to control the pressure of buffer tank 7. When the value read by buffer tank 7 is higher than the upper limit, the recovery pump 4 and buffer tank valve 6 are closed; when the value read by buffer tank 7 is lower than the lower limit, the recovery pump 4 and buffer tank valve 6 are opened.

[0055] The gas coming out of buffer tank 7 is partly compressed by compressor 9 and sent to gas storage device, and partly sent to degradation branch, where it is discharged after degradation.

[0056] The compressor 9 is connected to the buffer tank 7. The compressor 9 is used to further compress the gas coming out of the buffer tank 7. After compression, the gas passes through the filter 11 and is stored in the gas cylinder (tank) through the gas storage interface 13.

[0057] The compressor 9 preferably uses an oil-free scroll pump or an oil-free screw pump, which has a higher cleanliness of recovered gas than the compressor that uses an oil-containing pump.

[0058] A filter 11 is connected to the rear end of the compressor 9. The recovered gas passes through the filter 11, which can ensure the cleanliness of the gas entering the gas storage device (such as a high-pressure steel cylinder).

[0059] An air storage valve 10 is provided between the compressor 9 and the filter 11.

[0060] The gas storage interface 13 is connected to the filter 11. The filtered gas is stored in the gas storage device (such as a high-pressure steel cylinder) through the gas storage interface 13. A third pressure controller 12 is installed at the gas storage interface 13. The third pressure controller 12 is used to read the sulfur hexafluoride pressure in the gas storage device to protect the gas storage device from overload. When the pressure of the gas storage device exceeds the set pressure limit, the recovery operation is suspended. After replacing the gas storage device (high-pressure steel cylinder), the operation can continue until the operation is completed.

[0061] The degradation branch includes a thermal degradation tower 16, a heat exchanger 18, an acid-base neutralization tower 20, and a tail gas measurement chamber 21, which are connected in sequence by pipelines, wherein: The thermal degradation tower 16 is connected to the buffer tank 7 via the degradation valve 14. The thermal degradation tower 16 is located before the compressor 09 and is mainly used for the thermocatalytic degradation of sulfur hexafluoride gas. A gas flow meter 15 is installed between the degradation valve 14 and the thermal degradation tower 16, and a first axial flow fan 17 is installed on the thermal degradation tower 16.

[0062] The heat exchanger 18 is connected to the inlet and outlet of the thermal degradation tower 16. The heat exchanger 18 is used for heat exchange between the inlet air and the outlet air of the thermal degradation tower 16, thereby achieving the purpose of preheating the inlet air and cooling the outlet air. A second axial flow fan 19 is installed on the heat exchanger 18.

[0063] After being degraded by the thermal degradation tower 16, the gas enters the acid-base neutralization tower 20. After being neutralized by acid and base, the exhaust gas is detected by the exhaust gas measurement chamber 21. It is then discharged after meeting environmental protection requirements.

[0064] As a preferred embodiment, such as Figure 6 As shown, in the sulfur hexafluoride gas recovery device of the present invention, all valves (first vent valve 03, second vent valve 05, buffer tank valve 06, gas storage valve 10, degradation valve 14) are solenoid valves, and are connected to each actuator (first vent valve 03, second vent valve 05, buffer tank valve 06, gas storage valve 10, degradation valve 14, first pressure controller 02, second pressure controller 08, third pressure controller 12, recovery pump 4, compressor 9, thermal degradation tower 16, first axial flow fan 17, second axial flow fan 19, tail gas measuring chamber 21) via electrical signals, thereby realizing the automated control of the sulfur hexafluoride recovery and degradation device of the present invention.

[0065] The sulfur hexafluoride recovery and degradation device of the present invention can employ independent recovery and combined recovery and degradation functions, as detailed below: (1) Independent recycling Gas recovery path: The gas passes sequentially through recovery interface 1, recovery pump 4, buffer tank valve 6, buffer tank 7, compressor 9, gas storage valve 10, filter 11, and gas storage interface 13, and is then pressed into the gas storage device (high-pressure steel cylinder).

[0066] The specific operation is as follows: When using the independent recovery function, the high-voltage insulation equipment containing the sulfur hexafluoride gas to be recovered is connected to the sulfur hexafluoride recovery and degradation device of this invention through a pipe with the corresponding interface. The first pressure controller 2 reads the pressure inside the high-voltage insulation equipment cavity and sequentially opens the buffer tank valve 6, the recovery pump 4, the compressor 9, and the gas storage valve 10, while closing the degradation valve 14. The recovered gas is then pumped into the gas storage device (high-pressure cylinder) through the gas storage interface 13. When the pressure read by the first pressure controller 2 is lower than the specified final recovery pressure, the buffer tank valve 6 and the recovery pump 4 are closed. When the pressure read by the second pressure controller 8 is lower than the specified final recovery pressure, the compressor 9 and the gas storage valve 10 are closed, and the device completes the recovery operation. The third pressure controller 12 is used to read the sulfur hexafluoride pressure in the gas storage device to protect the gas storage device from overload. When the pressure in the gas storage device exceeds the set pressure limit, the recovery operation is paused. After replacing the gas storage device (high-pressure cylinder), the operation can continue until the operation is completed.

[0067] (2) Combined recycling and degradation The combined recycling and degradation function includes two parts: recycling the gas in the cavity and filling the cavity with air—degrading the gas in the cavity by evacuating it.

[0068] Gas recovery path: The gas passes sequentially through recovery interface 1, recovery pump 4, buffer tank valve 6, buffer tank 7, compressor 9, gas storage valve 10, filter 11, and gas storage interface 13, and is then pressed into the gas storage device (high-pressure steel cylinder).

[0069] Gas degradation path: The gas passes sequentially through recovery interface 1, recovery pump 4, buffer tank valve 6, buffer tank 7, degradation valve 14, gas flow meter 15, thermal degradation tower 16, heat exchanger 18, acid-base neutralization tower 20, and tail gas measurement chamber 21, and is then discharged.

[0070] The specific operation is as follows: The function and control of gas recovery within the chamber remain unchanged. Simultaneously with the start of recovery, the heating function of the thermal degradation tower 16 is activated, and the temperature rises to the set temperature after the degradation operation begins. After the recovery operation is completed, the first pressure controller 2 reads the pressure within the high-voltage insulation equipment chamber after recovery and a period of stabilization. Upon reading this pressure, it controls the opening of the first vent valve 3 to fill the chamber with air. After filling, the chamber contains a mixture of air and residual sulfur hexafluoride. After the temperature of the thermal degradation tower 16 reaches the set temperature, the gas storage valve 10 is closed, and the degradation valve 14, recovery pump 4, and buffer tank valve 6 are opened. The gas sequentially passes through the recovery interface 1, recovery pump 4, buffer tank valve 6, buffer tank 7, degradation valve 14, gas flow meter 15, thermal degradation tower 16, heat exchanger 18, acid-base neutralization tower 20, and tail gas measurement chamber 21 for degradation. When the first pressure controller 2 reads the set pressure, the recovery and degradation function is completed. Preferably, the process of filling the cavity with air and evacuating the gas inside the cavity to degrade it can be repeated multiple times to achieve near-zero emissions of sulfur hexafluoride.

[0071] It should be noted that before performing the recycling or recycling-degradation function, the gas inside the recycling and degradation combined device should be evacuated.

[0072] Application testing:

[0073] Based on the aforementioned sulfur hexafluoride (SF6) recovery and degradation combined process and device for high-voltage insulation equipment, experiments were conducted below based on SF6 emissions (SF6 content), treatment time, and near-zero emissions, respectively. Figure 1 The existing sulfur hexafluoride gas recovery process for high-voltage insulation equipment is shown as a control.

[0074] 1. Experimental setup: like Figure 6 The diagram shows the experimental design of the combined sulfur hexafluoride recovery and degradation of high-voltage insulation equipment according to the present invention: a 300L gas tank is used to simulate the gas chamber of the high-voltage insulation equipment after positive pressure recovery. The tank contains 0.1MPa sulfur hexafluoride gas (hereinafter referred to as the gas storage tank), the interface is DN8, and the gas pipe is 5 meters long. The combined sulfur hexafluoride recovery and degradation device is connected to the gas storage tank. A portion of the recovered gas is stored in the 300L gas tank (hereinafter referred to as the recovery tank), and a portion of the gas is discharged after degradation.

[0075] The degradation method for sulfur hexafluoride gas is a thermocatalytic degradation method: the degradation temperature of the thermal degradation tower is 600℃, and the degradation catalyst is a manganese-based catalytic material.

[0076] The preparation method of manganese-based catalytic material is as follows: manganese metal is used as the active site center, silicon carbide is used as the support for manganese metal, the mass ratio of support to manganese metal is controlled at 4:1, manganese metal and silicon carbide are mixed and then ground to obtain powdered manganese-based catalytic material.

[0077] 2. Experimental steps: (1) Start the recovery and degradation combined function of the sulfur hexafluoride recovery and degradation combined device, and first recover the 0.1MPa sulfur hexafluoride gas in the chamber to 0.01MPa (10kPa).

[0078] (2) Then fill the cavity with air to make the cavity pressure reach 0.1 MPa (corresponding to a sulfur hexafluoride gas concentration of 10% in the equipment cavity).

[0079] (3) Use a pump set to extract the mixture of sulfur hexafluoride gas and air in the cavity and perform degradation treatment until the cavity pressure is 0.01 MPa.

[0080] Repeat steps (2) to (3) several times until the target requirement is met.

[0081] 3. Experimental Results: (1) Based on sulfur hexafluoride emissions This experiment mainly tests the treatment time of different treatment processes based on a sulfur hexafluoride emission rate of 1%.

[0082] According to Part 1 of the existing "Technical Conditions for Sulfur Hexafluoride Gas Recovery Devices": after recovery, a maximum concentration of 13,300 ppm remains in each cubic meter of chamber, which is equivalent to a sulfur hexafluoride content of 1.33%. For the convenience of experimental statistics, this experiment uses a sulfur hexafluoride emission rate of 1% as the baseline.

[0083] like Figure 1 As shown, the existing sulfur hexafluoride gas recovery process for high-voltage insulation equipment is as follows: S1, Positive Pressure Recovery: The sulfur hexafluoride gas in the cavity of the high-voltage insulation equipment was recovered from an initial pressure of ≤0.8MPa to 0.1MPa.

[0084] S2, Negative Pressure Recovery: When the residual pressure in the high-voltage insulation equipment cavity reaches 0.1 MPa, it continues to be recovered to 1.33 × 10⁻⁶ MPa. -3 MPa (1.33 kPa).

[0085] S3, Equipment Maintenance Inject air to 0.1 MPa and perform equipment maintenance.

[0086] The existing sulfur hexafluoride (SF6) gas recovery process for high-voltage insulation equipment achieves 100% recovery in the positive pressure section and 98.67% recovery in the negative pressure section. The emission rate in the negative pressure section is 1.33%, and the SF6 content in the cavity after being flushed with air is 1.33%, or 13300 ppm. Testing shows that the total time for SF6 gas to recover from 0.1 MPa to 1.33 kPa is approximately 145 minutes. The relationship between process recovery time and pressure is shown in the graph below. Figure 2 As shown.

[0087] Combination Figure 1 and Figure 2 It can be seen that, with the existing recycling process, without considering the pressure rebound inside the chamber and the gas adhesion to the chamber wall, the time to reduce atmospheric pressure to 1 kPa (i.e., 1% sulfur hexafluoride emission rate) is approximately 145 minutes.

[0088] The recycling and degradation combined process of the present invention, combined with Figure 7 , Figure 8 As shown: The combined recycling and degradation process of this invention reduces the gas treatment time compared to existing recycling processes, and adds degradation technology without wasting gas. After recycling to 0.01 MPa in step (2), air is introduced into the cavity to 0.1 MPa (e.g., Figure 7 As shown in the image, the cavity at this point contains a mixture of 10% residual sulfur hexafluoride gas and air. By extracting and degrading this mixture, the pressure inside the cavity is reduced to 0.01 MPa, at which point the residual sulfur hexafluoride content in the cavity is 1%. The extracted mixture of sulfur hexafluoride gas and air, as shown... Figure 8 As shown, the degradation rate can reach 100% using the thermocatalytic degradation process of the present invention. The combined recycling and degradation process of the present invention, with complete degradation in the degradation steps and the same overall emission rate, has a processing time of approximately 115 minutes, which is 30 minutes shorter than existing recycling processes.

[0089] (2) Based on processing time This experiment mainly tests the degradation effect of sulfur hexafluoride gas under a treatment time of 145 minutes.

[0090] According to the existing "Technical Conditions for Sulfur Hexafluoride Gas Recovery Device": the gas achieves 100% recovery in the positive pressure section, 98.67% recovery rate in the negative pressure section, and a 1.33% emission rate in the negative pressure section. After being flushed with air, the sulfur hexafluoride content in the chamber is 1.33%, or 13300 ppm. The total time for recovering sulfur hexafluoride gas from 0.1 MPa to 1.33 kPa is approximately 145 minutes.

[0091] Based on a processing time of 145 minutes, the recycling and degradation process of the present invention was used to test its recycling and degradation effect, and compared with the existing process.

[0092] like Figure 9 As shown: In the combined recycling and degradation process of the present invention, the first step is the recycling process from 100 kPa to 10 kPa (minute 58), the second step is the degradation process from 100 kPa to 10 kPa (minute 116), and based on the processing time of 145 minutes, the third degradation can recover the gas in the chamber to 30 kPa (minute 145). That is, the concentration in the chamber is 10% after the first flushing with air, 1% after the second, and 0.3% after the third.

[0093] Compared with the existing recycling process of 145 minutes and an emission rate of 1.33%, the recycling and degradation combined process of the present invention can reduce emissions by about 70%.

[0094] (3) Near-zero emission test This experiment is based on achieving near-zero emissions of sulfur hexafluoride through multiple cycles, without considering treatment time.

[0095] like Figure 10 As shown, after one recovery process from 100 kPa to 10 kPa and five cycles of inflation and deflation degradation, the concentration of sulfur hexafluoride in the chamber is less than 1 ppm, achieving near-zero emissions.

[0096] (4) Adjust the final degradation pressure This experiment mainly investigates the treatment effect of sulfur hexafluoride under different final degradation pressures, including the following steps: S1. Recover sulfur hexafluoride gas in the cavity of the high-voltage insulation equipment from an initial pressure ≤0.8MPa to 0.1MPa.

[0097] S2. When the residual pressure inside the high-voltage insulation equipment reaches 0.1MPa, continue to recover to 0.01MPa (10kPa).

[0098] S3. Fill the cavity of the high-voltage insulation equipment with air to bring the cavity pressure to 0.1 MPa (corresponding to a sulfur hexafluoride gas concentration of 10% in the equipment cavity).

[0099] S4. Use a pump set to extract the mixture of sulfur hexafluoride gas and air from the cavity and perform degradation treatment until the cavity pressure is 0.03 MPa.

[0100] S5. After repeating steps S3 and S4 several times, open the equipment for maintenance.

[0101] In this embodiment, considering that the negative pressure extraction process takes longer at lower pressures, the final recovery pressure in the recovery and degradation process is set to 10 kPa to ensure the recovery rate of sulfur hexafluoride gas. The final degradation pressure in the degradation process is set to 30 kPa to save time as much as possible and increase the number of dilution cycles to achieve near-zero emissions. Figure 11 As shown: Under the condition that the final degradation pressure is set to 30 kPa, after 9 degradation dilutions, the concentration of sulfur hexafluoride in the cavity is about 1 ppm.

[0102] The above embodiments are merely illustrative examples of the present invention and do not constitute a limitation on the scope of protection of the present invention. The scope of protection of the present invention shall be determined by the claims.

Claims

1. A combined process for the recovery and degradation of sulfur hexafluoride in high-voltage insulation equipment, characterized in that, Includes the following steps: (1) Preliminary recovery of sulfur hexafluoride gas in the cavity of high-voltage insulation equipment; (2) After the initial recovery is completed, air is introduced into the equipment cavity; (3) Extract the mixture of residual sulfur hexafluoride gas and air from the cavity and degrade it; (4) After repeating steps (2) and (3) once or more, open the equipment for maintenance.

2. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (1): the initial pressure in the cavity of the high-voltage insulation equipment is ≤0.8Mpa.

3. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (1): the preliminary recovery is to extract sulfur hexafluoride gas from the cavity of the high-voltage insulation equipment until the cavity pressure is 0.01 MPa.

4. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (1): the initial recovery first recovers the sulfur hexafluoride gas in the cavity of the high-voltage insulation equipment from the initial pressure ≤0.8MPa to 0.1MPa, and when the residual pressure in the cavity of the high-voltage insulation equipment reaches 0.1MPa, it continues to recover to 0.01MPa.

5. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (2): After the initial recovery is completed, air is introduced into the equipment cavity until the cavity pressure reaches 0.1 MPa.

6. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (3): the mixture of residual sulfur hexafluoride gas and air in the cavity is extracted until the cavity pressure is 0.01-0.05 MPa.

7. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (3): the degradation is any one of plasma degradation, thermocatalytic degradation or photocatalytic degradation.

8. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: In step (3): the degradation is a thermocatalytic degradation, and the thermocatalytic degradation process conditions are as follows: the degradation temperature is 600℃, and the degradation catalyst is a manganese-based catalytic material.

9. The combined process for sulfur hexafluoride recovery and degradation in high-voltage insulation equipment according to claim 1, characterized in that: The preparation method of the manganese-based catalytic material is as follows: using manganese metal as the active site center, silicon carbide as the support for manganese metal, controlling the mass ratio of support to manganese metal to be 4:1, mixing manganese metal and silicon carbide, and then grinding to obtain powdered manganese-based catalytic material.

10. A combined device for the recovery and degradation of sulfur hexafluoride in high-voltage insulation equipment, characterized in that, It includes a main recovery path and a degradation branch path. The main recovery path includes a recovery interface, a recovery pump, a buffer tank, a compressor, a filter, and a gas storage interface connected in sequence through pipelines. The degradation branch path includes a thermal degradation tower, a heat exchanger, an acid-base neutralization tower, and a tail gas measurement chamber connected in sequence through pipelines.

11. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The recovery interface is used to connect to the vent of the high-voltage insulation equipment from which sulfur hexafluoride is to be recovered, and the recovery pump is a gas-powered system for recovery and degradation.

12. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 11, characterized in that: A first pressure controller and a first vent valve are connected in the pipeline between the recycling interface and the recycling pump.

13. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The buffer tank is used to store the gas recovered from the recovery pump. A second vent valve and a buffer tank valve are installed between the buffer tank and the recovery pump. A second pressure controller is connected to the buffer tank.

14. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The gas coming out of the buffer tank is partly compressed by the compressor and sent to the gas storage interface, and partly sent to the degradation branch, where it is discharged after degradation.

15. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 14, characterized in that: The compressor is connected to the buffer tank. The compressor is used to further compress the gas coming out of the buffer tank. After compression, the gas passes through a filter and is stored in the gas storage device through the gas storage interface.

16. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 14, characterized in that: The compressor is an oil-free scroll pump or an oil-free screw pump.

17. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: A filter is connected to the rear end of the compressor, and an air storage valve is installed between the compressor and the filter.

18. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The gas storage interface is connected to the filter. The filtered gas is stored in the gas storage device through the gas storage interface. A third pressure controller is installed at the gas storage interface.

19. A sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The thermal degradation tower is connected to the buffer tank via a degradation valve. The thermal degradation tower is used for the thermocatalytic degradation of sulfur hexafluoride gas. A gas flow meter is installed between the degradation valve and the thermal degradation tower.

20. A sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The heat exchanger is connected to the thermal degradation tower and is used for heat exchange between the inlet air and the outlet air of the thermal degradation tower.

21. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The gas degraded by the thermal degradation tower enters the acid-base neutralization tower. After acid-base neutralization treatment, the exhaust gas is tested by the exhaust gas measurement chamber. It is discharged after meeting environmental protection requirements.

22. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 10, characterized in that: The sulfur hexafluoride recovery and degradation device includes independent recovery and combined recovery and degradation functions: (1) Independent recycling Gas recovery path: The gas passes through the recovery interface, recovery pump, buffer tank valve, buffer tank, compressor, gas storage valve, filter, and gas storage interface in sequence, and then is pressed into the gas storage device. When using the independent recovery function, the high-voltage insulation equipment for recovering sulfur hexafluoride gas is connected to the sulfur hexafluoride recovery and degradation device of the present invention through the corresponding interface. The first pressure controller reads the pressure inside the high-voltage insulation equipment cavity and sequentially opens the buffer tank valve, recovery pump, compressor, and gas storage valve, closes the degradation valve, and pressurizes the recovered gas into the gas storage device through the gas storage interface. (2) Combined recycling and degradation The combined recycling and degradation function includes two parts: recycling the gas in the cavity and filling the cavity with air—degrading the gas in the cavity by evacuating it. Gas recovery path: The gas passes through the recovery interface, recovery pump, buffer tank valve, buffer tank, compressor, gas storage valve, filter, and gas storage interface in sequence, and then is pressed into the gas storage device. Gas degradation path: The gas passes sequentially through the recovery interface, recovery pump, buffer tank valve, buffer tank, degradation valve, gas flow meter, thermal degradation tower, heat exchanger, acid-base neutralization tower, and tail gas measurement chamber before being discharged; When recycling and degradation are combined, the function and control of gas recovery within the chamber remain unchanged. Simultaneously with gas recovery, the heating function of the thermal degradation tower is activated, and the temperature rises to the set temperature after the degradation operation begins. After the recycling operation is completed, the first pressure controller reads the pressure within the high-voltage insulation equipment chamber after recycling and stabilization for a period of time. Upon reading this pressure, the first vent valve is opened to fill the chamber with air. After filling, the chamber contains a mixture of air and residual sulfur hexafluoride. Once the thermal degradation tower temperature reaches the set temperature, the gas storage valve is closed, and the degradation valve, recycling pump, and buffer tank valve are opened. The gas sequentially passes through the recycling interface, recycling pump, buffer tank valve, buffer tank, degradation valve, gas flow meter, heat exchanger, thermal degradation tower, heat exchanger, acid-base neutralization tower, and tail gas measurement chamber. When the first pressure controller reads the set pressure, the recycling and degradation function is complete.

23. The sulfur hexafluoride recovery and degradation combined device for high-voltage insulation equipment according to claim 22, characterized in that: By repeatedly filling the cavity with air and then evacuating and degrading the gas inside the cavity, near-zero emissions of sulfur hexafluoride can be achieved.

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