Mixed insulating gas containing perfluorodimethyl sulfide and application thereof

Abstract

The invention relates to a gas insulation technology of an electric power system, in particular to a mixed insulating gas containing perfluorodimethyl sulfide and application of the mixed insulating gas. The insulating mixed gas is composed of a component 1 and a component 2, and the component 1 is perfluoromethyl sulfide; and the component 1 is 1, 1, 2, 2-tetrafluoroethane, 2, 3, 3, 3-tetrafluoropropene and 1, 1-difluoroethane, and the component 2 is 1, 1, 2, 2-tetrafluoroethane, 2, 3, 3, 3-tetrafluoropropene and 1, 1-difluoroethane. The insulating mixed gas provided by the invention has the insulating property equivalent to or even more excellent than that of sulfur hexafluoride, has a lower GWP value, and is particularly suitable for gas-insulated electrical transformers, gas-insulated wires for transmitting or distributing electric power, or connectors / disconnectors in the middle-high voltage field. The mixed gas disclosed by the invention has the characteristics similar to that of single gas, and the liquefaction temperature of the insulating mixed gas is lower than that of each component; and the mixed gas also has an insulating synergistic effect, and has the advantages of low GWP, low toxicity, low boiling point and high insulating strength.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical insulation, and in particular to an environmentally friendly insulating gas and application thereof in insulating or arc-extinguishing electrical equipment. Background Art

[0002] Perfluoromethyl sulfide (CF3SCF3, CAS: 371-78-8) is a new type of environmentally friendly insulating gas with an insulation strength of about 1.7 times that of sulfur hexafluoride, and its estimated GWP is only 2.8 times that of carbon dioxide. In addition, it has low toxicity, will not damage the ozone layer, and can be stored stably in the atmosphere. The boiling point of perfluoromethyl sulfide gas is -22°C, which is significantly better than most existing sulfur hexafluoride alternative gases.

[0003] However, compared with sulfur hexafluoride (relative insulation strength of 1, liquefaction temperature of -56°C, GWP of 23900), perfluoromethyl sulfide has lower GWP and higher insulation strength, but the liquefaction temperature is still high. Patent CN 118352919 A ​​discloses that its mixture with background gas can be used as an insulating gas to replace sulfur hexafluoride. However, the mixing scheme of perfluoromethyl sulfide and background gas can reduce the liquefaction temperature of the mixed gas, but the introduction of background gas will reduce the insulation strength of perfluoromethyl sulfide. The mixing ratio of background gas will affect both the liquefaction temperature and insulation strength. The replacement gas still needs further optimization. Summary of the invention

[0004] In view of the defects or shortcomings of the prior art, the present invention provides a mixed insulating gas containing perfluoromethyl sulfide.

[0005] The mixed insulating gas provided by the present invention comprises component 1 and component 2, wherein component 1 is perfluoromethyl sulfide; and component 2 is 1,1,2,2-tetrafluoroethane, 2,3,3,3-tetrafluoropropylene or 1,1-difluoroethane.

[0006] Furthermore, the dielectric strength of the mixed gas is Er_ 混合气体 Satisfies the relationship shown in formula (a):

[0007] Er_ 混合气体 >Er_ 组元1 ×x1+Er_ 组元2 ×x2 (a)

[0008] In the formula, Er_ 组元1 is the insulation strength of gas component 1 relative to SF6; Er_ 组元2 is the insulation strength of gas component 2 relative to SF6; x1 is the mass percentage of component 1 in the mixed gas; x2 is the mass percentage of component 2 in the mixed gas.

[0009] Optionally, the mass percentage of component 1 is 9.4% to 75.5%, and the mass percentage of component 2 is 24.5% to 90.6%.

[0010] Optionally, the insulating gas comprises component 3, which is at least one of nitrogen, oxygen, air and carbon dioxide. Optionally, based on 100% by mass, the mass percentages of component 1, component 2 and component 3 in the insulating mixed gas are: 9.3% to 43.4%: 46% to 89.9%: 0% to 28%, respectively, and the mass percentage of component 3 is greater than 0.

[0011] The mixed insulating gas of the present invention can be used in gas-insulated electrical transformers, gas-insulated wires for transmitting or distributing electric power, connectors or disconnectors. The working voltage of the mixed insulating gas is 3kV to 35kV, 35kV to 330kV or 330kV to 1200kV.

[0012] Component 1 and component 2 used in the present invention are both substances with low greenhouse effect potential (GWP value); component 1 is perfluoromethyl sulfide, the insulation strength of which is 1.7 times that of SF6, the atmospheric life is short, the toxicity is low, the GWP value is only 8, and the liquefaction temperature is -20°C; component 2 is one of 1,1,2,2-tetrafluoroethane, cis-1,3,3,3-tetrafluoropropylene, and 3,3,3-trifluoropropylene.

[0013] When the gas combination formed by component 1 and component 2 in the mixed gas of the present invention meets the screening conditions S1 to S3, an insulating gas similar to a single substance in macroscopic properties can be formed, which has a lower liquefaction temperature than individual components 1 and 2. DETAILED DESCRIPTION

[0014] Unless otherwise specified, the scientific and technical terms used herein are understood by ordinary technicians in the relevant fields. Based on the components 1 and 2 described in the present invention, in a specific solution, a mixed gas with specific components and specific proportions can be obtained by comprehensive consideration of the insulating properties, liquefaction temperature and greenhouse effect of these gases.

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Embodiment 1:

[0017] This embodiment is a screening process of gas component 2 of the present invention, and the specific screening method includes:

[0018] In the following screening method, the component i is perfluoromethyl sulfide, and the component j is component 2, wherein the component j is screened and determined by the following steps:

[0019] S1, select the insulating gas with a liquefaction temperature range of -40 to 20°C under standard atmospheric pressure as the initial component j;

[0020] S2, find at least one set of T, x under a given equilibrium pressure P, where the mixed gas of component i and initial component j is in gas-liquid equilibrium and satisfies the following formulas (1) to (16): i ,y i 、x j and j ; Where: the given equilibrium pressure P is the working pressure of SF6 gas, the unit of P is: MPa; T is the gas-liquid equilibrium temperature, the unit is ℃; x i is the molar percentage of gas component i in the liquid phase of the mixed gas; i is the molar percentage of gas component i in the gas phase of the mixed gas; x j is the molar percentage of gas component j in the liquid phase of the mixed gas; j is the molar percentage of gas component j in the gas phase of the mixed gas; -40℃≤T≤20℃, 0<x i <1,0<y i <1,0<x j <1,0<y j <1, and x i +x j =1,y i +y j =1;

[0021]

[0022]

[0023] α(T ri )=[1+(β2+β3ω i -β4ω i 2 )(1-T ri 1 / 2 )] 2 ,

[0024] 0.30000≤β2≤0.40000,

[0025] 1.50000≤β3≤1.60000,

[0026] 0.20000≤β4≤0.30000 (12)

[0027]

[0028] 0.40000≤β6≤0.50000,

[0029] 0.30000≤β7≤0.40000,

[0030] 1.50000≤β8≤1.60000,

[0031] 0.20000≤β9≤0.30000

[0032] In formulas (1)-(16):

[0033] is the gas phase fugacity of gas component i in the mixed gas, is the liquid phase fugacity of gas component i in the mixed gas, is the gas phase fugacity of gas component j in the mixed gas;

[0034] is the liquid phase fugacity of gas component j in the mixed gas;

[0035] R is the gas constant;

[0036] Z L is the gas phase compressibility factor of the mixed gas, Z V is the liquid phase compressibility factor of the mixed gas, V L is the molar volume of the liquid phase of the mixed gas under the conditions of P and T, in m 3 / mol; V V is the gas phase molar volume of the mixed gas under P and T conditions, in m 3 / mol; V is the volume of the mixed gas under the conditions of P and T, in m 3 ;

[0037] N i is the molar amount of gas component i in the mixed gas, in mol;

[0038] N j is the molar amount of gas component j in the mixed gas, in mol;

[0039] N is the total molar amount of the mixed gas, in mol;

[0040] a and b are the state equation parameters of the mixed gas;

[0041] a i is the molecular energy constant of gas component i, ranging from 12000 to 3845000; bi is the volume correction constant of gas component i, ranging from 12.85 to 140.68;

[0042] is the free energy of the gas mixture;

[0043] k ij is the binary interaction parameter, 0<k ij <5;

[0044] C is a constant, ranging from 24.68500 to 24.68600;

[0045] ω i is the eccentricity factor of gas component i, which is taken as 0.335;

[0046] ω j is the eccentricity factor of gas component j;

[0047] T ri is the relative state temperature of gas component i; the value range is 0.5~1;

[0048] T ci is the critical temperature of gas component i; the unit is K, and it is 376.75K;

[0049] T cj is the critical temperature of gas component j; unit: K;

[0050] p ci is the critical pressure of gas component i, in MPa; take 3.843MPa;

[0051] p cj is the critical pressure of gas component j, in MPa;

[0052] P i sat is the saturated vapor pressure of gas component i at temperature T, in MPa;

[0053] is the saturated vapor pressure of gas component j at temperature T, in MPa;

[0054] V i L is the liquid volume of gas component i under conditions of P and T, in m 3 ;

[0055] is the liquid volume of gas component j under conditions P and T, in m 3 ;

[0056] T / K is the temperature after the equilibrium temperature T is converted into Kelvin;

[0057] N gi All the groups decomposed from the molecules of gas component i, CF3SCF3 as the whole group; N gi The value is 1.

[0058] N gj All the groups decomposed by the molecules of gas component j;

[0059] k represents the molecular group CF3SCF3 of gas component i;

[0060] l represents any group among the groups decomposed by the molecules of gas component j;

[0061] α ik is the relative molar fraction of the group CF3SCF3, which is the value of the number of groups CF3SCF3 divided by the total number of groups in the gas component i molecule, and is 1;

[0062] α jk is the relative molar fraction of the group CF3SCF3 of the gas component j, which is the value of the number of groups CF3SCF3 divided by the total number of groups in the gas component j molecule;

[0063] α il is the relative molar fraction of group l of gas component i, which is the number of groups l divided by the total number of groups in the molecules of gas component i;

[0064] α jl is the relative molar fraction of group l of gas component j, which is the number of groups l divided by the total number of groups in the gas component j molecule;

[0065] A kl With B kl are the group parameters of the group CF3SCF3 and the group l;

[0066]

[0067] In the formula, A wk _CH2 is the interaction parameter between the ethylene group and the group 1; A wk _CH2 is the interaction parameter between the ethylene group and the group 1; N l is the number of positively charged atoms in group l;

[0068] S3, based on the screening results of S2, further screen the existence of x under the given equilibrium pressure P. i =y i Under the condition, the equilibrium temperature T is the minimum equilibrium temperature, and the minimum equilibrium temperature is less than the liquefaction temperature of each gas component in the mixed gas.

[0069] The screening range of component j in this embodiment is shown in Table 1, including perfluoromethyl sulfide (A), trifluoroiodomethane (B), cis-1,3,3,3-tetrafluoropropylene (C), 1,1-difluoroethane (D), 3,3,3-trifluoropropylene (E), 1,1,2,2-tetrafluoroethane (F), 2,3,3,3-tetrafluoropropylene (G), and heptafluoroisobutyronitrile (H), a total of 8 gases.

[0070] Table 1 Step S1 Gas Combination Screening Results

[0071] gas serial number Liquid temperature / ℃ Perfluoromethyl sulfide A -22 Trifluoroiodomethane B -25 cis-1,3,3,3-tetrafluoropropene C 9 1,1-Difluoroethane D -52 3,3,3-Trifluoropropene E -28 1,1,2,2-Tetrafluoroethane F -23 2,3,3,3-Tetrafluoropropene G 9 Heptafluoroisobutyronitrile H -7

[0072] According to the condition of S1, 7 gases are used as initial component j; further based on MATLAB software, the method screening calculation of the above steps S2 and S3 is performed, and P is taken as p=0.1MPa in the process (in other specific schemes, P can be taken according to the working pressure of the insulating gas, and 0.1MPa is selected as an example here to explain the present invention in detail; the common working pressure of the insulating mixed gas described in the present invention is 0.1MPa~0.5MPa); the screening results are shown in Table 2;

[0073] The results screened by the conditions of steps S2 and S3 are: perfluoromethyl sulfide+1,1-difluoroethane, perfluoromethyl sulfide+1,1,2,2-tetrafluoroethane, perfluoromethyl sulfide+2,3,3,3-tetrafluoropropylene, a total of 3 mixed gases.

[0074] During the screening process, the value of C was 24.68544; Take 1.1001; Take 1.3741; a i Take 1645070; b i Take 40.78; T ri Take 0.8; β1=-0.62323, β2=0.37464, β3=1.54226, β4=0.26992, β5=0.07780, β6=0.45724, β7=0.37464, β8=1.54226, β9=0.26992;

[0075] Table 2 Calculation results of the screening gas combinations in steps S2 and S3 at 0.1 MPa

[0076]

[0077] In order to meet the use scenarios with higher insulation strength, a further preferred solution is to use formula (a) to screen mixed gases with synergistic effect characteristics in insulation strength.

[0078] The following examples prepare mixed gases of perfluoromethyl sulfide+1,1,2,2-tetrafluoroethane, perfluoromethyl sulfide+2,3,3,3-tetrafluoropropylene, and perfluoromethyl sulfide+1,1-difluoroethane in different ratios, and conduct insulation strength experimental measurements.

[0079] Embodiment 2:

[0080] Under a temperature condition of -40°C, 45.5% by mass of perfluoromethyl sulfide and 54.5% by mass of 1,1-difluoroethane are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0081] Embodiment 3:

[0082] Under a temperature condition of -40°C, 45.5% by mass of perfluoromethyl sulfide and 54.5% by mass of perfluoromethyl sulfide + 1,1,2,2-tetrafluoroethane are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0083] Embodiment 4:

[0084] Under a temperature condition of -40°C, 48.5% by mass of perfluoromethyl sulfide and 61.9% by mass of perfluoromethyl sulfide + 1,1,2,2-tetrafluoroethane are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0085] Embodiment 5:

[0086] Under a temperature condition of -40°C, 55.5% by mass of perfluoromethyl sulfide and 44.5% by mass of 2,3,3,3-tetrafluoropropylene are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0087] Embodiment 6:

[0088] Under the temperature condition of -40°C, 63.5% by mass of perfluoromethyl sulfide and 36.5% by mass of 2,3,3,3-tetrafluoropropylene are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0089] Embodiment 7:

[0090] Under a temperature condition of -40°C, 70.5% by mass of perfluoromethyl sulfide and 29.5% by mass of 2,3,3,3-tetrafluoropropylene are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0091] Embodiment 8:

[0092] Under a temperature condition of -40°C, 75.5% by mass of perfluoromethyl sulfide and 24.5% by mass of 2,3,3,3-tetrafluoropropylene are physically mixed under liquid phase conditions and completely gasified to obtain a mixed insulating gas.

[0093] Comparative Example 1:

[0094] Perfluoromethyl sulfide with a mass percentage of 100% was used as the insulating gas.

[0095] Comparative Example 2:

[0096] 1,1-difluoroethane with a mass percentage of 100% was used as the insulating gas.

[0097] Comparative Example 3:

[0098] 1,1,2,2-tetrafluoroethane with a mass percentage of 100% was used as the insulating gas.

[0099] Comparative Example 4:

[0100] 100% by mass of 2,3,3,3-tetrafluoropropylene was used as the insulating gas.

[0101] After the temperature of the liquid mixture of the above embodiment rises to room temperature and is completely gasified, the insulation strength of the gas in the above embodiment and each comparative example relative to SF6 gas is tested under the condition of an inter-electrode spacing of 0.1 inches. The results are shown in Table 3; wherein the GWP value is based on CO2 as a reference value of 1.0 (100 years), and the insulation strength is based on sulfur hexafluoride as a reference value.

[0102] According to the EU standard EN14756 [European standard. Determination of the limiting oxygen concentration (LOC) for gases and vapours: EN 14756-2007 [S]. Berlin: European committee for standardization, 2006.], a flammability test device was built, and the results are shown in Table 1;

[0103] The liquefaction temperatures of the embodiments and comparative examples were measured by observation method, and the results are shown in Table 3. As can be seen from Table 3, the present invention has a lower liquefaction temperature.

[0104] Table 3 Comparison of environmental performance and insulation strength

[0105]

[0106]

[0107] As can be seen from Table 3, the greenhouse effect potential (GWP) value of the above embodiment is also much smaller than that of sulfur hexafluoride, which is more in line with the current environmental protection requirements for reducing the global warming effect. In terms of liquefaction temperature, the liquefaction temperature range of the mixed gas is -55 to -25°C, which is much smaller than that of perfluoroisoamyl ketone (C5F 10 O), perfluoroisobutyronitrile and other g3 gases are suitable for high-voltage switchgear and other insulating equipment, and are not suitable for liquefaction in cold northern regions; in terms of flammability, the mixed gas inhibits the combustion performance of the combustible components in a single gas, making its macroscopic properties similar to the non-flammability of a single substance.

Claims

1. A mixed insulating gas containing perfluoromethyl sulfide, characterized in that: The mixed insulating gas comprises component 1 and component 2, wherein component 1 is perfluoromethyl sulfide; and component 2 is 1,1,2,2-tetrafluoroethane, 2,3,3,3-tetrafluoropropylene or 1,1-difluoroethane.

2. The mixed insulating gas containing perfluoromethyl sulfide according to claim 1, characterized in that: The dielectric strength of the mixed gas is Er_ 混合气体 Satisfies the relationship shown in formula (a): Is_ 混合气体 > Is_ 组元1 × x1+ Is_ 组元2 × x2 (a) In the formula, Er_ 组元1 is the insulation strength of gas component 1 relative to SF6; Er_ 组元2 is the insulation strength of gas component 2 relative to SF6; x1 is the mass percentage of component 1 in the mixed gas; x2 is the mass percentage of component 2 in the mixed gas.

3. The mixed insulating gas containing perfluoromethyl sulfide according to claim 1, characterized in that: The mass percentage of component 1 is 9.4% to 75.5%, and the mass percentage of component 2 is 24.5% to 90.6%.

4. The mixed insulating gas containing perfluoromethyl sulfide according to claim 1, characterized in that: The insulating gas contains component 3, and component 3 is at least one of nitrogen, oxygen, air and carbon dioxide.

5. The mixed insulating gas containing perfluoromethyl sulfide according to claim 5, characterized in that: Taking the mass percentage as 100%, the mass percentages of component 1, component 2 and component 3 of the insulating mixed gas are respectively: 9.3% to 43.4%: 46% to 89.9%: 0% to 28%, and the mass percentage of component 3 is greater than 0.

6. Use of the mixed insulating gas according to any one of claims 1 to 5 in a gas-insulated electrical transformer, a gas-insulated line for transmitting or distributing electric power, a connector or a disconnector.

7. The use according to claim 6, characterized in that: The working voltage of the mixed insulating gas is 3kV to 35kV.

8. The use according to claim 6, characterized in that: The working voltage of the mixed insulating gas is 35kV to 330kV.

9. The use according to claim 6, characterized in that: The working voltage of the mixed insulating gas is 330 kV to 1200 kV.

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