Insulating gas containing perfluoromethyl sulfide and use thereof in insulating or arc-extinguishing power device

Abstract

The present invention relates to the field of insulating gases, and disclosed are an insulating gas containing perfluoromethyl sulfide and a use thereof in an insulating or arc-extinguishing power device. The insulating gas is CF3SCF3 or a mixed gas thereof with a carrier gas, and is applied to the field of insulating or arc-extinguishing power devices, and the good insulating performance of the insulating gas can prevent electric arcs from burning through the power devices. The perfluoromethyl sulfide provided in the present application has an insulation strength 1.73 times that of sulfur hexafluoride, has a positive insulation synergistic effect with the carrier gas, has a boiling point of -22°C, and has an estimated GWP only 2.8 times that of carbon dioxide, which is much lower than the GWP (25200) of sulfur hexafluoride. The perfluoromethyl sulfide has the advantages of low GWP, low toxicity, low boiling point and high insulation strength, not only meets the insulation strength required by power device applications, but also ensures extremely low environmental damage, and reduces greenhouse gas emission. The comprehensive indicators of the perfluoromethyl sulfide are superior to those of most existing sulfur hexafluoride alternative gases.

Description

Insulating gas containing perfluoromethane sulfide and its use in insulating or arc extinguishing electrical equipment TECHNICAL FIELD

[0001] The present application relates to the field of insulating gas, in particular to an insulating gas containing perfluoromethane sulfide and its use in insulating or arc extinguishing electrical equipment. BACKGROUND

[0002] At present, sulfur hexafluoride (SF6) gas is the most widely used as a gas insulating medium in medium and high voltage arc extinguishing / insulating electrical equipment, which has excellent insulating and arc extinguishing performance. At the same time, the gas is chemically inert, non-toxic, non-flammable, non-explosive and thermodynamically stable. Therefore, SF6 and its mixed gas as an insulating and arc extinguishing medium occupies a dominant position in medium and high voltage electrical equipment in the power grid.

[0003] However, SF6 has a serious greenhouse effect, with a global warming potential (GWP) of about 25200 times that of CO2 and an atmospheric lifetime of about 3200 years, making it one of the strongest greenhouse gases known. Under the drive of the "double carbon" target, it is urgent to reduce the greenhouse gas emissions of electrical equipment, and it has become a technical problem to be solved by those skilled in the art to find an environmentally friendly sulfur hexafluoride substitute gas as an insulating gas medium for electrical equipment.

[0004] The sulfur hexafluoride substitute gases that have been found so far mainly include PFC gas, CF3I gas, heptafluoroisobutyronitrile (C4F7N), etc. The GWP of PFC gases such as c-C4F8, C2F6, C3F8 is still high, about 8700, 12200, and 7000 respectively. The GWP value of CF3I gas is comparable to that of CO2 gas, and its insulating strength is better than that of SF6 gas, with an advantage in dielectric strength and GWP value, but its atmospheric lifetime is only 1-2 days, and it is prone to decomposition in the application process, which affects the arc extinguishing and insulating performance, and it is also expensive. The GWP index of heptafluoroisobutyronitrile (C4F7N) is still relatively high (about 2100 times that of CO2), and the boiling point of heptafluoroisobutyronitrile is relatively high (-4.7℃), which requires the use of a large amount of buffer gas, limiting its further application. Therefore, the current sulfur hexafluoride substitute gases cannot achieve perfect replacement, and there is still great potential to find other potential sulfur hexafluoride substitute gases.

[0005] SUMMARY

[0006] The application provides an insulating gas containing perfluoromethane sulfide and application thereof in insulating or arc extinguishing power equipment, and proposes that the perfluoromethane sulfide is used as a substitute insulating gas of sulfur hexafluoride in power equipment, the perfluoromethane sulfide has low boiling point, GWP and toxicity, and the insulating strength thereof is about 1.73 times of that of sulfur hexafluoride, and has better performance compared with the current sulfur hexafluoride substitute gas.

[0007] To solve the above technical problems, one of the purposes of the application provides an insulating gas containing perfluoromethane sulfide, the insulating gas being CF3SCF3 or a mixed gas thereof with a carrier gas.

[0008] As a preferred scheme, the carrier gas is at least one of dry air, N2, CO2, O2 and noble gas.

[0009] As a preferred scheme, it comprises CF3SCF3 with a mole percentage of 3-100% and a mixed gas of N2 or N2 and O2 in the rest.

[0010] As a preferred scheme, it comprises CF3SCF3 with a mole percentage of 10-30% and a mixed gas of N2 or N2 and O2 in the rest.

[0011] As a preferred scheme, it comprises CF3SCF3 with a mole percentage of 3-100% and a mixed gas of CO2 or CO2 and O2 in the rest.

[0012] As a preferred scheme, it comprises CF3SCF3 with a mole percentage of 10-30% and a mixed gas of CO2 or CO2 and O2 in the rest.

[0013] As a preferred scheme, the insulating gas has CF3SCF3 and the carrier gas with a mole ratio of the insulating strength synergistic effect coefficient defined in formula (a) being above 0.1.

[0014] In formula (a), C is the synergistic effect coefficient, U mix is the insulating breakdown voltage of the insulating gas, k is the mole ratio of the perfluoromethane sulfide, U1 is the insulating breakdown voltage of the perfluoromethane sulfide, and U2 is the insulating breakdown voltage of the carrier gas.

[0015] To solve the above technical problems, the second purpose of the application provides application of the insulating gas containing perfluoromethane sulfide in the field of insulating or arc extinguishing power equipment.

[0016] To solve the above technical problems, the third purpose of the application provides a power switch device containing an insulating gas, and the insulating gas uses the above insulating gas containing perfluoromethane sulfide.

[0017] As a preferred solution, the operating temperature of the power switching device is above -25 DEG C, and the power switching device is a medium voltage switching device or a high voltage switching device.

[0018] As a preferred solution, the operating temperature of the power switching device is -25 DEG C to 40 DEG C.

[0019] As a preferred solution, the power switching device comprises a busbar, an instrument chamber, a cabinet, a gas density sensor, a disconnector, a load switch, a fuse, a three-position disconnector, a three-position disconnector operating mechanism, a grounding switch, a control and protection unit, a circuit breaker, a circuit breaker operating mechanism, a voltage transformer, a ZnO arrester, a current transformer, a switch cabinet, a gas insulated transformer, a gas insulated combined electric appliance, a gas insulated line, a busbar set or a power switch, a connecting piece and an outgoing terminal, a cable terminal, a pressure relief channel, an upper inflatable shell and a lower inflatable shell, and the gas medium is sealed in the upper inflatable shell and the lower inflatable shell.

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

[0021] 1. The gas insulation strength of the perfluoromethyl sulfide provided by the present application is about 1.73 times that of sulfur hexafluoride, and the boiling point thereof is -22 DEG C, which is lower than that of sulfur hexafluoride, but is significantly lower than the boiling points of other sulfur hexafluoride replacement gases. When applied to power equipment, the gas has high insulation strength and low charging pressure.

[0022] 2. When the perfluoromethyl sulfide of the present application is operated at an ambient temperature of -5 DEG C, only 0.21 MPa of perfluoromethyl sulfide needs to be charged into the power equipment to achieve the same insulation strength as a 0.35 MPa sulfur hexafluoride device. The estimated GWP of perfluoromethyl sulfide is only 2.8 times that of carbon dioxide, which has low GWP and toxicity. It can not only meet the required insulation strength of power equipment applications, but also ensure very low damage to the environment and reduce greenhouse gas emissions. It can be used as a sulfur hexafluoride replacement gas. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the molecular structure of the perfluoromethyl sulfide of the present application.

[0024] Figure 2 is a synergistic effect coefficient curve diagram of the insulating gas after mixing different proportions of perfluoromethyl sulfide with N2 or CO2 carrier gas. DETAILED DESCRIPTION

[0025] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0026] The perfluoromethane sulfide (CF3SCF3, CAS: 371-78-8) provided in the present application has a structural formula as shown in FIG. 1, and C2F6S can also be used as an alias of the perfluoromethane sulfide. The perfluoromethane sulfide has an insulation strength 1.73 times that of sulfur hexafluoride, and the estimated GWP is only 2.8 times that of carbon dioxide. As shown in Table 1, compared with SF6, the CF3SCF3 has a lower boiling point and GWP, and is low in toxicity. However, the boiling point of the perfluoromethane sulfide gas is -22℃, which is obviously better than that of most existing sulfur hexafluoride replacement gases. The perfluoromethane sulfide or a mixture thereof with a background gas can be used as a sulfur hexafluoride replacement insulation gas, and can meet the requirements of low boiling point, high insulation strength, low toxicity, and low GWP. The gas does not destroy the ozone layer, and can stably exist in the atmosphere.

[0027] Table 1-Comparison of properties of different insulation gases

[0028] Preparation Example 1

[0029] An insulation gas containing perfluoromethane sulfide includes 5% of perfluoromethane sulfide (CF3SCF3) by mole fraction and 95% of N2 by mole fraction.

[0030] Preparation Example 2

[0031] An insulation gas containing perfluoromethane sulfide includes 10% of perfluoromethane sulfide (CF3SCF3) by mole fraction and 90% of N2 by mole fraction.

[0032] Preparation Example 3

[0033] An insulation gas containing perfluoromethane sulfide includes 20% of perfluoromethane sulfide (CF3SCF3) by mole fraction and 80% of N2 by mole fraction.

[0034] Preparation Example 4

[0035] An insulation gas containing perfluoromethane sulfide includes 30% of perfluoromethane sulfide (CF3SCF3) by mole fraction and 70% of N2 by mole fraction.

[0036] Preparation Example 5

[0037] An insulation gas containing perfluoromethane sulfide includes 40% of perfluoromethane sulfide (CF3SCF3) by mole fraction and 60% of N2 by mole fraction.

[0038] Preparation Example 6

[0039] An insulating gas containing perfluoromethanethiol, comprising 60% by mole of perfluoromethanethiol (CF3SCF3) and 40% by mole of N2.

[0040] Preparation Example 7

[0041] An insulating gas containing perfluoromethanethiol, comprising 80% by mole of perfluoromethanethiol (CF3SCF3) and 20% by mole of N2.

[0042] Preparation Example 8

[0043] An insulating gas containing perfluoromethanethiol, comprising 5% by mole of perfluoromethanethiol (CF3SCF3) and 95% by mole of CO2.

[0044] Preparation Example 9

[0045] An insulating gas containing perfluoromethanethiol, comprising 10% by mole of perfluoromethanethiol (CF3SCF3) and 90% by mole of CO2.

[0046] Preparation Example 10

[0047] An insulating gas containing perfluoromethanethiol, comprising 15% by mole of perfluoromethanethiol (CF3SCF3) and 85% by mole of CO2.

[0048] Preparation Example 11

[0049] An insulating gas containing perfluoromethanethiol, comprising 20% by mole of perfluoromethanethiol (CF3SCF3) and 80% by mole of CO2.

[0050] Preparation Example 12

[0051] An insulating gas containing perfluoromethanethiol, comprising 40% by mole of perfluoromethanethiol (CF3SCF3) and 60% by mole of CO2.

[0052] Preparation Example 13

[0053] An insulating gas containing perfluoromethanethiol, comprising 60% by mole of perfluoromethanethiol (CF3SCF3) and 40% by mole of CO2.

[0054] Preparation Example 14

[0055] An insulating gas containing perfluoromethanethiol, comprising 80% by mole of perfluoromethanethiol (CF3SCF3) and 20% by mole of CO2.

[0056] Example 1

[0057] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -15°C, the insulating gas comprising 20% by mole of perfluoromethane sulfide (CF3SCF3) and 80% by mole of N2, at this time the insulating gas has a gas filling pressure of 0.7 MPa, a critical breakdown field strength of about 53 kV / mm, and a GWP of 0.56.

[0058] Example 2

[0059] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -25°C, the insulating gas comprising 7% by mole of perfluoromethane sulfide (CF3SCF3) and 93% by mole of N2, at this time the insulating gas has a gas filling pressure of 1.4 MPa, a critical breakdown field strength of about 53 kV / mm, and a GWP of 0.20.

[0060] Example 3

[0061] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -15°C, the insulating gas comprising 10% by mole of perfluoromethane sulfide (CF3SCF3) and 90% by mole of CO2, at this time the insulating gas has a gas filling pressure of 1.1 MPa, a critical breakdown field strength of about 54 kV / mm, and a GWP of 1.18.

[0062] Example 4

[0063] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -25°C, the insulating gas comprising 10% by mole of perfluoromethane sulfide (CF3SCF3) and 90% by mole of CO2, at this time the insulating gas has a gas filling pressure of 0.7 MPa, a critical breakdown field strength of about 34 kV / mm, and a GWP of 1.18.

[0064] Example 5

[0065] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -15°C, the insulating gas comprising 10% by mole of perfluoromethane sulfide (CF3SCF3) and 90% by mole of N2, at this time the insulating gas has a gas filling pressure of 1.35 MPa, a critical breakdown field strength of about 70 kV / mm, and a GWP of 0.28.

[0066] Example 6

[0067] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -15°C, the insulating gas comprising 30% by mole of perfluoromethane sulfide (CF3SCF3) and 70% by mole of N2, at this time the insulating gas has a gas filling pressure of 0.45 MPa, a critical breakdown field strength of about 40 kV / mm, and a GWP of 0.84.

[0068] Example 7

[0069] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -15°C, the insulating gas comprising perfluoromethane sulfide (CF3SCF3) at a mole fraction of 30% and CO2 at a mole fraction of 70%, at this time the insulating gas having a gas filling pressure of 0.48 MPa, a critical breakdown field strength of about 28 kV / mm, and a GWP of 1.54.

[0070] Example 8

[0071] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -25°C, the insulating gas comprising perfluoromethane sulfide (CF3SCF3) at a mole fraction of 5% and N2 at a mole fraction of 95%, at this time the insulating gas having a gas filling pressure of 1.7 MPa, a critical breakdown field strength of about 60 kV / mm, and a GWP of 0.14.

[0072] Example 9

[0073] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -25°C, the insulating gas comprising perfluoromethane sulfide (CF3SCF3) at a mole fraction of 10% and N2 at a mole fraction of 90%, at this time the insulating gas having a gas filling pressure of 0.87 MPa, a critical breakdown field strength of about 44 kV / mm, and a GWP of 0.28.

[0074] Example 10

[0075] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -5°C, the insulating gas comprising perfluoromethane sulfide (CF3SCF3), at this time the insulating gas having a gas filling pressure of 0.21 MPa, a critical breakdown field strength of about 32 kV / mm, and a GWP of 2.8. Comparative Example 1

[0076] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -15°C, the insulating gas comprising C4F7N at a mole fraction of 10% and CO2 at a mole fraction of 90%, at this time the insulating gas having a gas filling pressure of 0.6 MPa, a critical breakdown field strength of about 42 kV / mm, and a GWP of 210.9.

[0077] Comparative Example 2

[0078] A power apparatus containing an insulating gas, the operating temperature of the power apparatus being -25°C, the insulating gas comprising C4F7N at a mole fraction of 10% and CO2 at a mole fraction of 90%, at this time the insulating gas having a gas filling pressure of 0.38 MPa, a critical breakdown field strength of about 26 kV / mm, and a GWP of 210.9.

[0079] Comparative Example 3

[0080] A power equipment containing an insulating gas, the operating temperature of the power equipment is -15℃, the insulating gas comprises C4F7N with a mole fraction of 30% and N2 with a mole fraction of 70%, at this time the inflation pressure of the insulating gas is 0.02 MPa, the critical breakdown field strength is about 3.1 kV / mm, and the GWP is 630.

[0081] Comparative Example 4

[0082] A power equipment containing an insulating gas, the operating temperature of the power equipment is -15℃, the insulating gas comprises C4F7N with a mole fraction of 30% and CO2 with a mole fraction of 70%, at this time the inflation pressure of the insulating gas is 0.2 MPa, the critical breakdown field strength is about 23 kV / mm, and the GWP is 630.

[0083] Comparative Example 5

[0084] A power equipment containing an insulating gas, the operating temperature of the power equipment is -25~ -5℃, the insulating gas comprises SF6 with a mole fraction, at this time the inflation pressure of the insulating gas is 0.6 MPa, the critical breakdown field strength is about 53 kV / mm, and the GWP is 25200.

[0085] Comparative Example 6

[0086] A power equipment containing an insulating gas, the operating temperature of the power equipment is -5℃, the insulating gas comprises SF6 with a mole fraction, at this time the inflation pressure of the insulating gas is 0.35 MPa, the critical breakdown field strength is about 30 kV / mm, and the GWP is 25200.

[0087] It can be known from the comparison of the schemes of Examples 3-4 and Comparative Examples 1-2 and Examples 6-7 and Comparative Examples 3-4 that the boiling point of the perfluoromethyl sulfide of the application is obviously lower than that of heptafluoroisobutyronitrile, the power equipment can meet the operation in a lower environment temperature, and the perfluoromethyl sulfide has a positive synergistic effect with the carrier gas, although the insulation strength of the perfluoromethyl sulfide is lower than that of heptafluoroisobutyronitrile, but when the perfluoromethyl sulfide and heptafluoroisobutyronitrile are filled with the same mole fraction, the insulation strength of the perfluoromethyl sulfide mixed with the carrier gas is obviously higher than that of heptafluoroisobutyronitrile mixed with the carrier. It can be known from the comparison of the schemes of Examples 1 and Comparative Example 5 that the perfluoromethyl sulfide of the application has a positive synergistic effect with the carrier gas, and the synergistic effect with nitrogen is more significant, in Example 1, only 20% of the perfluoromethyl sulfide and 80% of nitrogen need to be filled, so that the insulation strength of sulfur hexafluoride in Comparative Example 5 can be reached under similar inflation pressure, and the GWP of the insulating gas of the application is lower.

[0088] Performance detection test

[0089] 1. The insulation strength of the gas insulation medium prepared in Preparation Examples 1-14 was detected at room temperature, and the synergistic effect coefficient was calculated using the following formula (1), and the calculation results are shown in Figure 2 and Table 2-3.

[0090] In formula (1), C is the synergistic effect coefficient, U mix is the insulation breakdown voltage of the mixed gas, k is the mixing ratio (molar ratio) of component 1 gas, U1 and U2 represent the insulation breakdown voltage of pure component 1 and component 2, respectively.

[0091] Table 2-Insulation strength test results of perfluoromethanethioether and nitrogen mixed gas in Preparation Examples 1-7

[0092] Table 3-Insulation strength test results of perfluoromethanethioether and carbon dioxide mixed gas in Preparation Examples 8-14

[0093] As shown in Table 2 and Figure 2, when perfluoromethanethioether is mixed with N2 as a carrier gas, the insulation strength can achieve a higher synergistic effect when the molar percentage of perfluoromethanethioether is in the range of 5-40%, and the highest synergistic effect is achieved when the molar percentage of perfluoromethanethioether is 20%. Since perfluoromethanethioether and N2 gas have a positive synergistic effect, the insulation strength of the mixed insulation gas is higher when it is filled in power equipment, and the breakdown field strength is also higher, which can further reduce the filling pressure and improve the breakdown field strength.

[0094] As shown in Table 3 and Figure 2, when perfluoromethanethioether is mixed with CO2 as a carrier gas, the insulation strength can achieve a higher synergistic effect when the molar percentage of perfluoromethanethioether is in the range of 10-20%, and the highest synergistic effect is achieved when the molar percentage of perfluoromethanethioether is 15%. Since perfluoromethanethioether and CO2 gas have a positive synergistic effect, the insulation strength of the mixed insulation gas is higher when it is filled in power equipment, and the breakdown field strength is also higher, which can further reduce the filling pressure and improve the breakdown field strength.

[0095] In addition, perfluoromethanethioether has sufficient thermal stability. In a tube furnace heating experiment, CF3SCF3 did not show obvious decomposition at 400℃, and only a little decomposition was observed at 450℃ for a long time. At 550℃, there was relatively obvious decomposition, but the degree of decomposition was still limited. Considering that the operating temperature of the equipment will not exceed 100℃ under normal operating conditions, perfluoromethanethioether has sufficient stability as an insulation medium.

[0096] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An insulating gas containing perfluoromethane thioether, characterized in that, The insulating gas is CF3SCF3 or a mixture thereof with a carrier gas.

2. An insulating gas containing perfluoromethane sulfide according to claim 1, characterized in that, The carrier gas is at least one of dry air, N2, CO2, O2 and a noble gas.

3. An insulating gas containing perfluoromethane sulfide according to claim 1, characterized in that, It comprises CF3SCF3 at a molar percentage of 3-100% and a balance of N2 or a mixture of N2 and O2.

4. An insulating gas containing perfluoromethane thioether according to claim 1, characterized in that, It comprises CF3SCF3 at a molar percentage of 10-30% and a balance of N2 or a mixture of N2 and O2.

5. An insulating gas containing perfluoromethane thioether according to claim 1, characterized in that, It comprises CF3SCF3 at a molar percentage of 3-100% and a balance of CO2 or a mixture of CO2 and O2.

6. An insulating gas containing perfluoromethane thioether according to claim 1, characterized in that, It comprises CF3SCF3 at a molar percentage of 10-30% and a balance of CO2 or a mixture of CO2 and O2.

7. An insulating gas containing perfluoromethane sulfide according to claim 1, characterized in that, The insulating gas has a CF3SCF3 and carrier gas molar ratio satisfying the dielectric strength synergistic effect coefficient defined by formula (a) of 0.1 or more; In formula (a), C is a synergistic effect coefficient, U mix is the insulation breakdown voltage of the insulating gas, k is the molar proportion of perfluoromethane sulfide, U1 is the insulation breakdown voltage of perfluoromethane sulfide, and U2 is the insulation breakdown voltage of the carrier gas.

8. Use of the insulating gas containing perfluoromethane sulfide according to any one of claims 1-7 in the field of insulating or arc extinguishing electric power equipment.

9. An insulated and / or arc extinguishing electric device containing an insulating gas, characterized in that, The insulating and / or arc extinguishing electric power equipment is a gas insulated transformer, a gas insulated combined electric appliance, a gas insulated line, a busbar assembly or a power switch.

10. Insulating and / or arc extinguishing electrical power apparatus containing an insulating gas according to claim 9, characterized in that The insulating and / or arc extinguishing electric power equipment has an operating temperature of -25°C or higher, and is a medium voltage switchgear or a high voltage switchgear.

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