Hybrid gas insulation medium, gas insulated switchgear and method of manufacturing thereof

Abstract

The application discloses a mixed gas insulation medium, a gas insulation switch device and a preparation method of the mixed gas insulation medium. The mixed gas insulation medium comprises the following gas components in percentage by volume: 20-25% of CF3SO2F, 3-5% of O2 and 70-77% of N2. The mixed gas insulation medium can effectively reduce the greenhouse effect, and the insulation strength is equivalent to that of SF6, so that the safe operation of the power equipment can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas insulated switchgear, and more particularly to a mixed gas insulation medium, a gas insulated switchgear and a preparation method thereof. BACKGROUND

[0002] Electrical equipment using gas insulation usually uses SF6 as the insulation medium. However, SF6 is a very strong greenhouse gas, and its global warming potential (GWP) is 23900 times that of CO2. Moreover, due to the extremely stable chemical properties of SF6, its existence time in the atmosphere can be as long as 3200 years, and it basically does not decompose naturally once it leaks into the atmosphere, thus having a cumulative effect on global warming. According to monitoring, the content of SF6 in the global atmospheric environment has increased from 3.67 x 10 -7 % in 1994 to 10.41 x 10 -7 % in 2020, an increase of 265%, and the global atmospheric environment content of SF6 has increased by 16.3% in the past five years alone. The global temperature rise caused by SF6 has reached 0.004℃, and is showing an upward trend. In the Kyoto Protocol signed in 1997, it is clear that CO2, CH4, N2O, PFC, HFC and SF6 belong to the scope of greenhouse gases, and developed countries are required to first freeze the emission of greenhouse gases at the level in the 1990s. Therefore, it is urgent to find a suitable environmentally friendly insulation medium to replace SF6, which not only ensures similar insulation performance to SF6, but also meets the industrial use requirements of non-toxicity, non-flammability and the like, and does not have a negative impact on the environment. SUMMARY

[0003] The present application aims to overcome the problem of greenhouse effect caused by the use of SF6 gas in the prior art, and provides a mixed gas insulation medium containing environmentally friendly gas CF3SO2F, a gas insulated switchgear and a preparation method thereof, which can effectively reduce the greenhouse effect, and has an insulation strength comparable to SF6, thereby ensuring the safe operation of power equipment.

[0004] To achieve the above-mentioned purpose, the technical solutions of the present application are as follows:

[0005] A mixed gas insulation medium comprises the following gas components in volume percentage: 20% to 25% of CF3SO2F, 3% to 5% of O2 and 70% to 77% of N2.

[0006] The present application also discloses a gas insulated switchgear, comprising a sealed container and a mixed gas insulation medium as described above sealed in the sealed container.

[0007] The application further discloses a preparation method of the gas insulated switchgear.

[0008] A sealed container is provided, and the sealed container is vacuumized.

[0009] CF3SO2F, O2 and N2 are filled into the sealed container, wherein the volume percentage of the CF3SO2F in the sealed container is 20-25%, the volume percentage of the O2 is 3-5%, and the volume percentage of the N2 is 70-77%.

[0010] The gas insulated switchgear is obtained through standing.

[0011] The application has the following beneficial effects:

[0012] The application selects CF3SO2F as the insulation medium, and the CF3SO2F is an environment-friendly insulation gas, which is colorless, odorless, non-flammable and non-explosible, and the decomposition products in the current breaking condition are low-toxic or non-toxic substances, and will not cause serious harm to the human body, and will not cause damage to the ozone layer, and the CF3SO2F has excellent electrical performance, and the insulation strength can reach more than 1.7 times of that of SF6 under the same pressure, and the CF3SO2F can completely replace SF6, and is more environment-friendly than SF6, and the global warming potential value is only 0.2‰ of the global warming potential value of SF6, and the N2 is a buffer gas, and is mainly used for reducing the liquefaction temperature of the mixed gas and enhancing the insulation performance of the whole, and the liquefaction temperature of the mixed gas formed finally can be reduced to about -30 DEG C, and can meet the use requirements in most areas of China, and the O2 is used for inhibiting the generation of the solid precipitate of carbon element and the gas decomposition products of the CF3SO2F discharge decomposition, and improving the reliability of the mixed gas application. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0014] In the formula, R represents a C1-C3 alkyl group, and X represents a halogen element.

[0015] Figure 1 is a schematic diagram of a molecular structure of CF3SO2F. DETAILED DESCRIPTION

[0016] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0017] The application discloses a mixed gas insulation medium, which comprises the following gas components in volume percentage: 20-25% of CF3SO2F, 3-5% of O2 and 70-77% of N2.

[0018] In the application, a molecular structure diagram of CF3SO2F is as shown in the figure. Figure 1 The CF3SO2F is affected by the halogen elements F and S in the molecule, has a strong adsorption effect on free electrons, can adsorb free electrons in the process of electron avalanche generated in the initial stage of discharge, and can inhibit the generation of collision ionization, so as to realize insulation.

[0019] The CF3SO2F is an environmentally friendly insulation gas, which is colorless, odorless, non-flammable and non-explosive, and the decomposition products under the condition of current breaking are low-toxic or non-toxic substances, which will not cause serious harm to the human body, and have little influence on the greenhouse effect. In addition, the CF3SO2F does not contain chlorine elements and bromine elements commonly used in refrigerants, and will not cause damage to the ozone layer. Moreover, the CF3SO2F has excellent electrical performance, and the insulation strength can reach more than 1.7 times of that of SF6 under the same gas pressure, so the CF3SO2F can completely replace SF6. In addition, compared with SF6 gas, the CF3SO2F is more environmentally friendly, and the global warming potential is only 0.2‰ of the global warming potential of SF6 gas.

[0020] Experimental research on the discharge decomposition characteristics of the CF3SO2F mixed gas shows that the CF3SO2F will be decomposed under the conditions of partial discharge dominated by electron collision ionization and spark and arc discharge dominated by collision ionization and high-temperature thermal ionization, and CO, perfluorocarbon and other small molecular decomposition products and elemental carbon are generated. The addition of O2 can inhibit the generation of solid precipitates and part of the gas decomposition products to a certain extent, and improve the reliability of the application of the mixed gas. N2 is a buffer gas, which is mainly used for reducing the liquefaction temperature of the mixed gas and enhancing the insulation performance of the whole. The liquefaction temperature of the finally formed mixed gas can be reduced to about -30 DEG C, which can meet the use requirements in most areas of China.

[0021] In a preferred embodiment, the mixed gas insulation medium comprises the following components in volume percentage: 25% of CF3SO2F, 5% of O2 and 70% of N2.

[0022] In some embodiments, the purity of CF3SO2F is greater than 99.99%, the purity of O2 is greater than 99.99%, and the purity of N2 is greater than 99.99%.

[0023] In some embodiments, the liquefaction temperature of the mixed gas insulation medium is -40℃ to -28℃, which can meet the use requirements in most areas of China.

[0024] The application further discloses a gas insulated switchgear, which comprises a sealed container and a mixed gas insulation medium as described above sealed in the sealed container.

[0025] In some embodiments, the upper part of the sealed container is provided with a first gas filling interface for filling CF3SO2F and O2 into the sealed container, and the lower part of the sealed container is provided with a second gas filling interface for filling N2 into the sealed container, the CF3SO2F and O2 with large density are filled from the upper part, and the N2 with small density is filled from the lower part, so that the standing time after mixing can be reduced, and the gas mixing can be more uniform.

[0026] In some embodiments, the lower part of the sealed container is further provided with a gas extraction interface for vacuumizing the sealed container.

[0027] It is worth noting that the above-mentioned "upper part" refers to the upper part of the sealed container, including the top of the sealed container and the upper part of the side wall, and the above-mentioned "lower part" refers to the lower part of the sealed container, including the bottom of the sealed container and the lower part of the side wall.

[0028] In a specific embodiment, a first gas filling valve is arranged at the first gas filling interface, a second gas filling valve is arranged at the second gas filling interface, and a vacuumizing valve is arranged at the gas extraction interface.

[0029] The application further discloses a preparation method of the above-mentioned gas insulated switchgear, which comprises the following processes:

[0030] S1: providing a sealed container, and vacuumizing the sealed container.

[0031] Specifically, the vacuumizing valve is connected with a vacuum generator to vacuumize the sealed container, and the vacuum degree of the vacuumized sealed container can be less than 10 Pa. The arrangement position and connection relationship of the vacuumizing valve are as described above.

[0032] S2: filling CF3SO2F, O2 and N2 into the sealed container, wherein the volume percentage of CF3SO2F in the sealed container is 20% to 25%, the volume percentage of O2 is 3% to 5%, and the volume percentage of N2 is 70% to 77%.

[0033] Preferably, in this step, the sealed container is filled with CF3SO2F, O2 and N2, including the following processes:

[0034] S21: filling CF3SO2F and O2 from the upper part of the sealed container into the sealed container.

[0035] Specifically, CF3SO2F and O2 are filled into the sealed container through the first gas filling valve.

[0036] S22: filling N2 from the lower part of the sealed container into the sealed container.

[0037] Specifically, N2 is filled into the sealed container through the second gas filling valve.

[0038] S3: standing to make the mixed gas in the sealed container fully mixed and uniform, to obtain a gas insulated switchgear.

[0039] In some embodiments, the standing time is 12-16 hours.

[0040] Referring to Table 1, which is the formula of the mixed gas insulation medium of the specific embodiments, % means volume percentage.

[0041] Table 1: formula of the mixed gas insulation medium of each embodiment

[0042] CF3SO2F (%) O2 (%) [N2 (%)] 1 25 5 70 2 20 3 77 3 22.5 4 73.5 4 15 5 80 5 25 0 75

[0043] The mixed gas insulation medium of each embodiment of Table 1 is subjected to performance testing.

[0044] In the same experimental device (metal sealed container with a height of less than 5 m), the sealed container is first pumped to a vacuum state below 10 Pa, and then CF3SO2F, O2 and N2 gases are sequentially filled, and the mixed gas is left to stand for 24 hours to mix uniformly. The mixed gas insulation medium is subjected to insulation test, with SF6 gas as a comparative example, test voltage being power frequency voltage and lightning impulse voltage, electrode being a sphere-plate electrode, electrode gap distance being 5 mm, and experimental gas pressure being 0.1-0.7 MPa. The experimental results are shown in Table 2.

[0045] Table 2: insulation test results of the mixed gas insulation medium of each embodiment

[0046]

[0047] From Table 2, it can be seen that the breakdown voltage of the mixed gas of Examples 1-3 is better than that of SF6under the same conditions, at least 1.06 times, and has good insulation characteristics. The content of CF3SO2F in the mixed gas of Example 4 is less than that of Examples 1-3 and 5, and therefore, the breakdown voltage at each gas pressure is lower than that of Examples 1-3 and 5. Therefore, 20-25% of CF3SO2F can provide a better breakdown voltage.

[0048] The global warming potential value (GWP) of the mixed gas insulation medium was calculated according to the global warming potential value (GWP) of each gas component, and the results are shown in Table 3. It is known that the GWP of CF3SO2F is 3687, the GWP of N2 is 0, and the GWP of O2 is 0. CF3SO2F N2 O2 The global warming potential value (GWP) of the mixed gas insulation medium was calculated according to the global warming potential value (GWP) of each gas component, and the results are shown in Table 3. It is known that the GWP of CF3SO2F is 3687, the GWP of N2 is 0, and the GWP of O2 is 0.

[0049] GWP = V CF3SO2F * GWP CF3SO2F + V N2 * GWP N2 + V O2 * GWP O2

[0050] In the formula, V CF3SO2F represents the volume percentage of CF3SO2F, V N2 represents the volume percentage of N2, and V O2 represents the volume percentage of O2.

[0051] The liquefaction temperature of the mixed gas was obtained by vapor pressure tester, and the results are shown in Table 3.

[0052] Before and after the discharge test, the gas was taken using a sampling bag and subjected to gas chromatography mass spectrometry detection, the change of the gas composition before and after the test can be obtained, and the gas decomposition rate can be obtained, and the results are shown in Table 3.

[0053] The size of the flat plate electrode used in each discharge test was the same, and after each experiment, the adhered solid particles and dust on the surface of the plate electrode were scraped off using a brush, and the weight was measured to obtain the mass of the solid precipitate, and the results are shown in Table 3.

[0054] Table 3: Performance indicators of the mixed gas insulation medium of each example

[0055] GWP Liquefaction temperature (°C) Decomposition rate Amount of solid precipitated 1 921.75 -28 5％ 32 mg 2 737.4 -40 9％ 39 mg 3 829.575 -34 7％ 33 mg 4 553.05 -49 5％ 20 mg 5 921.75 -28 11％ 43 mg SF6 23900 -62 No decomposition No precipitate

[0056] ​​From Table 3, it can be seen that: 1) the GWP value of the mixed gas insulation medium of Examples 1-5 is only about 3.85% of that of SF6 gas, and it can be seen that the GWP can be significantly reduced by replacing SF6 with CF3SO2F; 2) the mixed gas insulation medium of Example 5 does not contain O2, the decomposition rate is 11%, and the solid precipitation amount is 43 mg, and the decomposition rate and the solid precipitation amount are higher than those of Examples 1-4 in which O2 is added; 3) compared with Example 4, the volume content of CF3SO2F in Examples 1-3 is 20%-25%, while the volume content of CF3SO2F in Example 4 is 15%, and from Table 3, it can be seen that the decomposition rate and the solid precipitation amount of Example 4 are low due to the low volume content of CF3SO2F, and it can be seen that too high CF3SO2F content will lead to too high decomposition rate and solid precipitation amount, affecting the use stability of the insulation gas; 4) compared with Example 1, the volume content of CF3SO2F in Example 5 is the same, but the decomposition rate and the solid precipitation amount of Example 5 are much higher than those of Example 1 due to the lack of O2 component, and it can be seen that the increase of the O2 component can inhibit the decomposition of CF3SO2F and inhibit the solid precipitation; 5) with reference to Examples 1-5, among them, the N2 component content in Example 4 is the highest, and it has the lowest liquefaction temperature, and with the decrease of the N2 component content, the liquefaction temperature increases.

[0057] In summary, the breakdown voltage is high, the liquefaction temperature meets the use requirements of most areas in China, the decomposition rate is low, and the solid precipitate is less, preferably, the volume content of CF3SO2F is 20%-25%, the volume content of O2 is 3%-5%, and the volume content of N2 is 70%-77%.

[0058] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A mixed gas insulating medium, characterized by, It includes the following gaseous components by volume percentage: 20%–25% CF3SO2F, 3%–5% O2, and 70%–77% N2.

2. The mixed gas insulating medium according to claim 1, wherein It includes the following components by volume percentage: 25% CF3SO2F, 5% O2, and 70% N2.

3. The mixed gas insulating medium according to claim 1, wherein The liquefaction temperature of the mixed gas insulating medium is -40℃ to -28℃.

4. The mixed gas insulating medium according to claim 1, wherein The purity of the CF3SO2F is greater than 99.99%; The purity of the O2 is greater than 99.99%; The purity of the N2 is greater than 99.99%.

5. A gas insulated switchgear, characterized by It includes a sealed container and a mixed gas insulating medium as described in any one of claims 1 to 4, sealed within the sealed container.

6. The gas insulated switchgear of claim 5, characterized in that, The sealed container is provided with a first inflation port at the top, which is used to fill the sealed container with CF3SO2F and O2. The sealed container is provided with a second inflation port at the bottom, which is used to fill the sealed container with N2.

7. The gas insulated switchgear of claim 6, characterized in that The lower part of the sealed container is also provided with an air extraction port, which is used to evacuate the sealed container.

8. A method of manufacturing a gas-insulated switchgear, characterized in that, Includes the following processes: Provide a sealed container, and evacuate the sealed container; The sealed container is filled with CF3SO2F, O2 and N2, wherein the volume percentage of CF3SO2F in the sealed container is 20% to 25%, the volume percentage of O2 is 3% to 5%, and the volume percentage of N2 is 70% to 77%. After standing, the gas-insulated switchgear is obtained.

9. The method of producing a gas insulated switchgear according to claim 8, characterized in that, The process of filling the sealed container with CF3SO2F, O2, and N2 includes the following steps: The CF3SO2F and the O2 are filled into the sealed container from the top. The N2 is introduced into the sealed container from the bottom.

10. The method of producing a gas-insulated switchgear according to claim 8, characterized in that, The vacuum level of the sealed container is less than 10 Pa; The settling time is 12 to 16 hours.

Images