Insulating medium and preparation method and application thereof

Abstract

The invention provides an insulating medium and a preparation method and application thereof. The insulating medium comprises insulating gas and perfluoropolyether oil, the insulating gas comprises perfluoroisobutyronitrile or perfluoropentanone, the mass ratio of the perfluoropolyether oil to the insulating gas is (1: 10)-(1: 15), and the insulating medium can avoid corrosion when a metal material in electrical equipment is in contact with the insulating medium and has good insulating performance.

Description

Technical Field

[0001] The invention belongs to the technical field of gas insulation detection in power systems, and in particular relates to an insulating medium and a preparation method and application thereof. Background Art

[0002] Sulfur hexafluoride (SF6) gas has excellent insulation and arc extinguishing properties, so high-voltage switchgear uses SF6 gas as the insulation and breaking medium; however, the global warming potential (GWP) of SF6 gas is very high. According to the latest IPCC report, the GWP of 1 kg of SF6 is equivalent to 24,300 kg of CO2. In order to reduce the carbon footprint of high-voltage switchgear throughout its life cycle, researchers at home and abroad are looking for and selecting gases that can replace SF6. C4-FN (perfluoroisobutyronitrile) is one of the alternative gases. Compared with SF6 gas, the GWP100 value of C4-FN mixed gas is between 350-700, and its gas density is only 30%-60% of SF6 gas. Compared with the same amount of SF6 gas solution, it can reduce CO2 emissions by about 99%. Because C4-FN gas has high dielectric properties, the high-voltage switchgear body requires less raw materials, which can minimize greenhouse gas emissions, thereby ensuring a low carbon footprint of high-voltage switchgear throughout its life cycle.

[0003] However, in actual application, C4-FN is prone to corrode metal materials in electrical equipment, and corrode the surface or connections of equipment. This will not only deteriorate the performance of metal parts in the insulating equipment, leading to problems such as surface flashover voltage drop, gas leakage or frequent gas replenishment, but will also cause C4-FN to decompose and reduce its insulation performance. Summary of the invention

[0004] Aiming at the problem that C4-FN insulating medium is easy to corrode metal materials in electrical equipment, an insulating medium and a preparation method and application thereof are provided.

[0005] To solve the above technical problems, on the one hand, the present invention provides an insulating medium, including an insulating gas and perfluoropolyether oil, wherein the insulating gas includes perfluoroisobutyronitrile or perfluoropentanone, and the mass ratio of the perfluoropolyether oil to the insulating gas is (1:10) to (1:15).

[0006] Optionally, the perfluoropolyether oil includes one or more of K-type PFPE, Y-type PFPE, Z-type PFPE, and D-type PFPE.

[0007] Optionally, the molecular weight of the perfluoropolyether oil is 1000-10000 g / mol.

[0008] Optionally, the insulating medium further comprises an additive, wherein the additive comprises one or more of perfluoropolyether-modified amines and perfluoropolyether-modified thiazoles.

[0009] Optionally, the mass of the additive accounts for 0.2% to 2% of the mass of the perfluoropolyether oil. Optionally, the additive comprises one or more of Formula 1 to Formula 4, wherein R1 is selected from F, CF3, CF2CF3 or CF(CF3)CF3; R2 is selected from H, CH3 or Ph; Rf1, Rf2, and Rf3 are each independently selected from , m and n are integers of 5 to 30; Ar is an aromatic group; . Optionally, the insulating gas also includes one or two of O2, CO2 and N2.

[0010] Optionally, the insulating gas comprises the following components in molar percentage: 3% to 10% perfluoroisobutyronitrile, 5% to 10% O2 and 80% to 92% N2 and / or CO2.

[0011] In a second aspect, the present invention further provides a method for preparing the insulating medium as described above, comprising the following steps: Passing the perfluoropolyether oil and the insulating gas into an atomizer; The perfluoropolyether oil and the insulating gas are mixed and atomized by the atomizer to obtain the insulating medium.

[0012] In a third aspect, the present invention further provides a use of the insulating medium as described in any one of the above items as an electrically insulating atmosphere in a fluid-insulated power transmission device.

[0013] In the present invention, the insulating medium contains insulating gas and perfluoropolyether oil in a specific mass ratio, so that it can prevent the metal surface of the electrical insulation equipment from being corroded by perfluoroisobutyronitrile gas when the metal surface is treated. The perfluoropolyether oil blocks the metal material from contacting with the insulating gas while maintaining the strength and good conductivity of the metal material, thereby preventing the metal material from being corroded by perfluoroisobutyronitrile or perfluoropentanone at high temperature, and prolonging the service life of the electrical insulation equipment. Among them, the perfluoropolyether oil forms an antioxidant layer on the surface of the electrical equipment, reduces or eliminates contact with oxygen, and protects the surface of the electrical equipment intactly. At the same time, it has good insulation performance, which helps perfluoroisobutyronitrile or perfluoropentanone to achieve the insulation arc extinguishing function. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the electrode surface after the copper electrode breakdown test of Examples 1 to 11 and Comparative Examples 1 to 4. DETAILED DESCRIPTION

[0015] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] The insulating medium provided by the embodiment of the present invention includes an insulating gas and perfluoropolyether oil, wherein the insulating gas includes perfluoroisobutyronitrile or perfluoropentanone, and the mass ratio of the perfluoropolyether oil to the insulating gas is (1:10) to (1:15).

[0017] In this embodiment, the insulating medium contains insulating gas and perfluoropolyether oil in a specific mass ratio, so that it can prevent the metal surface of the electrical insulation equipment from being corroded by perfluoroisobutyronitrile gas when it is treated. The perfluoropolyether oil blocks the metal material from contacting with the insulating gas while maintaining the strength and good conductivity of the metal material, thereby preventing the metal material from being corroded by perfluoroisobutyronitrile or perfluoropentanone at high temperature, and extending the service life of the electrical insulation equipment. Among them, the perfluoropolyether oil forms an antioxidant layer on the surface of the electrical equipment, reduces or eliminates contact with oxygen, and protects the surface of the electrical equipment intactly. At the same time, it has good insulation performance, which helps perfluoroisobutyronitrile or perfluoropentanone to achieve the insulation arc extinguishing function.

[0018] In one embodiment, the perfluoropolyether oil includes one or more of K-type PFPE, Y-type PFPE, Z-type PFPE, and D-type PFPE. By selecting the above-mentioned perfluoropolyether oil with stable chemical properties, it will not react with corrosive chemical gases, will not affect the properties of the insulating gas, and will form an anti-oxidation layer on the surface of the equipment to protect the equipment, extend the service life of the equipment, and reduce the risk of equipment damage caused by chemical corrosion. In addition, the above-mentioned perfluoropolyether oil has good compatibility with electrode materials and sealing materials, avoiding adverse effects such as swelling and corrosion on rubber materials.

[0019] In a preferred embodiment, the perfluoropolyether oil is selected from K-type PFPE.

[0020] In one embodiment, the molecular weight of the perfluoropolyether oil is 1000-10000 g / mol. When the molecular weight of the perfluoropolyether oil is within the above range, the molecular chain length is moderate. In an insulating gas environment, this molecular chain length helps to form a more ordered arrangement structure under the action of an electric field. In high-voltage insulating equipment, the molecules can be better filled between gas molecules, effectively preventing the migration of electrons, thereby increasing the breakdown voltage of the insulating gas, enhancing the insulation performance, and reducing the occurrence of partial discharge.

[0021] Specifically, the molecular weight of the perfluoropolyether oil includes but is not limited to 1000-5000 g / mol, 5000-10000 g / mol.

[0022] In a preferred embodiment, the molecular weight of the perfluoropolyether oil is 6000-10000 g / mol.

[0023] In a preferred embodiment, the molecular weight of the perfluoropolyether oil is 10000 g / mol.

[0024] In one embodiment, the insulating medium further comprises an additive, wherein the additive comprises one or more of perfluoropolyether-modified amines and perfluoropolyether-modified thiazoles. The lone pair electrons of O, nitrogen and sulfur atoms in the additive can react with the metal to undergo chemical adsorption, forming a dense oil film on the metal surface to isolate the metal from the corrosive gas, thereby inhibiting metal corrosion.

[0025] In one embodiment, the mass of the additive accounts for 0.2%-2% of the mass of the perfluoropolyether oil. In one embodiment, the additive comprises one or more of Formula 1 to Formula 4, wherein R1 is selected from F, CF3, CF2CF3 or CF(CF3)CF3; R2 is selected from H, CH3 or Ph; Rf1, Rf2, and Rf3 are each independently selected from , m and n are integers of 5 to 30; Ar is an aromatic group; . In one embodiment, the insulating gas further comprises one or two of O2, CO2 and N2. Perfluoroisobutyronitrile mixed with a carrier gas (CO2 or N2) can reduce the liquefaction temperature of the insulating gas.

[0026] O2 is mainly used to reduce free carbon, a byproduct produced during the equipment manufacturing process, and to reduce the content of toxic byproduct CO in the gas after arcing. At the same time, O2 helps to improve the breaking performance of the circuit breaker, thereby achieving higher breaking performance under the same product size design.

[0027] Furthermore, the purity of each gas in the mixed gas is: Perfluoroisobutyronitrile content ≥99.3%, ≤270ppmv H2O; O2 content ≥99.5%, ≤200 ppmvH2O; CO2 content ≥99.5%, ≤200 ppmvH2O; N2 content ≥99.5%, ≤ 200 ppmvH2O.

[0028] In one embodiment, the insulating gas includes the following molar percentage components: 3% to 10% perfluoroisobutyronitrile, 5% to 10% O2, and 80% to 92% N2 and / or CO2. O2 is an oxidant, and the content of O2 should not exceed this range in order to avoid corrosion of the surface of the electrical equipment.

[0029] In a second aspect, an embodiment of the present invention further provides a method for preparing the insulating medium as described above, comprising the following steps: Passing the perfluoropolyether oil and the insulating gas into an atomizer; The perfluoropolyether oil and the insulating gas are mixed and atomized by the atomizer to obtain the insulating medium. Specifically, the atomizer is a jet atomizer.

[0030] In a third aspect, an embodiment of the present invention further provides a use of the insulating medium as described in any one of the above items as an electrically insulating atmosphere in a fluid-insulated power transmission device.

[0031] The present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Example 1 This embodiment is used to illustrate the insulating medium disclosed in the present invention.

[0033] Take 0.446g of perfluoropolyether oil (molecular weight 5000-10000g / mol) and put it into the jet atomizer, then fill it with perfluoropentanone C5FK: 0.31mpa, O2: 0.155mpa and N2 / CO2: 2.635mpa in sequence, and mix them physically at 25°C. The mixed gas is filled into the chamber through the jet atomizer. Among them, the insulating gas includes the following molar percentage components: 10% C5FK, 5% O2, 85% N2. The mass ratio of perfluoropolyether oil to insulating gas is 1:10.

[0034] Example 2 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 1, except that an additive of formula 2 is added to the perfluoropolyether oil, wherein R1 is CF3, and the mass of the additive is 4.66 mg.

[0035] Example 3 This embodiment is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 1, except that the molecular weight of the perfluoropolyether oil is 1000-5000 g / mol, and the insulating gas includes the following components in molar percentage: 10% perfluoroisobutyronitrile, 5% O2, and 85% N2.

[0036] Example 4 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that an additive of Formula 3 is added to the perfluoropolyether oil, wherein R2 is H, and the mass of the additive is 4.66 mg.

[0037] Example 5 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that the molecular weight of the perfluoropolyether oil is 5000-10000 g / mol.

[0038] Example 6 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that the molecular weight of the perfluoropolyether oil is 5000-10000 g / mol.

[0039] An additive of formula 1 is added to the perfluoropolyether oil, wherein Ar is phenyl and the mass of the additive is 4.66 mg.

[0040] Example 7 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that the mass ratio of perfluoropolyether oil to insulating gas is 1:13.

[0041] Example 8 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that the mass ratio of perfluoropolyether oil to insulating gas is 1:15.

[0042] Example 9 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 4, except that an additive of Formula 3 is added to the perfluoropolyether oil, wherein R2 is H, and the mass of the additive is 0.9 mg.

[0043] Example 10 This example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 4, except that an additive of Formula 3 is added to the perfluoropolyether oil, wherein R2 is H, and the mass of the additive is 9 mg.

[0044] Embodiment 11 This embodiment is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operation steps in Embodiment 4, except that the additive is the additive of Formula 4.

[0045] Comparative Example 1 This comparative example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 1, except that it does not contain perfluoropolyether oil.

[0046] Comparative Example 2 This comparative example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that it does not contain perfluoropolyether oil.

[0047] Comparative Example 3 This comparative example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that the mass ratio of perfluoropolyether oil to insulating gas is 1:9.

[0048] Comparative Example 4 This comparative example is used to illustrate the insulating medium disclosed in the present invention, and includes most of the operating steps in Example 3, except that the mass ratio of perfluoropolyether oil to insulating gas is 1:16.

[0049] Performance Testing Take a ball plate electrode model, an inflatable 1L sealed pressure-resistant container (the container contains 5 EPDM rubber tensile performance test dumbbell-shaped standard parts and 5 Shore hardness standard parts), and then evacuate the inside of the two to a vacuum state below 10Pa; then fill the insulating medium of the embodiment and the comparative example into the ball plate electrode model and the 1L sealed pressure-resistant container, so that the pressure in the electrode model cavity reaches 0.1MPa, and perform a 40kV power frequency breakdown voltage test; after the 1L sealed pressure-resistant container is inflated to normal pressure, the container is placed in a 100℃ environment for 48 hours. After 100 times of 40kV power frequency voltage breakdown test, observe the surface of the copper electrode; take the EPDM sample to test the tensile strength, hardness and elongation at break. The test results are shown in Table 1.

[0050] It can be seen from the data in Table 1 that after the rubber test in Comparative Examples 1 and 2, the hardness increased, the tensile strength and the elongation at break decreased, while the hardness, tensile strength and the elongation at break of the rubber in Examples 1 to 6 remained relatively stable. Figure 1 It can be seen that the insulating medium provided by the present invention can maintain the strength and good conductivity of the metal material while effectively slowing down the corrosion of the metal material.

[0051] It can be seen from the test results of Examples 3, 7-8 and Comparative Examples 3-4 in Table 1 that in the insulating medium, if the molar content of perfluoropolyether oil is too high or too low, the elongation at break of the rubber will be reduced, and the electrode surface after the breakdown test will easily turn black and discolor. It can be seen from the test results of Examples 4, 9 and 10 in Table 1 that as the additive content decreases or increases, the electrode surface after the breakdown test will slightly change color.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An insulating medium, characterized in that: It includes insulating gas and perfluoropolyether oil, wherein the insulating gas includes perfluoroisobutyronitrile or perfluoropentanone, and the mass ratio of the perfluoropolyether oil to the insulating gas is (1:10) to (1:15).

2. The insulating medium according to claim 1, characterized in that: The perfluoropolyether oil includes one or more of K-type PFPE, Y-type PFPE, Z-type PFPE, and D-type PFPE.

3. The insulating medium according to claim 1 or 2, characterized in that: The molecular weight of the perfluoropolyether oil is 1000-10000 g / mol.

4. The insulating medium according to claim 1, characterized in that: The insulating medium further comprises an additive, wherein the additive comprises one or more of perfluoropolyether-modified amines and perfluoropolyether-modified thiazoles.

5. The insulating medium according to claim 4, characterized in that: The mass of the additive accounts for 0.2% to 2% of the mass of the perfluoropolyether oil.

6. The insulating medium according to claim 4, characterized in that: The additive comprises one or more of Formula 1 to Formula 4, wherein R1 is selected from F, CF3, CF2CF3 or CF(CF3)CF3; R2 is selected from H, CH3 or Ph; Rf1, Rf2, and Rf3 are each independently selected from , m and n are integers of 5 to 30; Ar is an aromatic group; 。 7. The insulating medium according to claim 1, characterized in that: The insulating gas also includes one or two of O2, CO2 and N2.

8. The insulating medium according to claim 7, characterized in that: The insulating gas includes the following components in molar percentage: 3% to 10% perfluoroisobutyronitrile, 5% to 10% O2, 80% to 92% N2 and / or CO2.

9. The method for preparing an insulating medium according to claims 1 to 8, characterized in that: The following steps are involved: introducing the perfluoropolyether oil and the insulating gas into an atomizer; The perfluoropolyether oil and the insulating gas are mixed and atomized by the atomizer to obtain the insulating medium.

10. Use of the insulating medium according to any one of claims 1 to 8 as an electrically insulating atmosphere in a fluid-insulated power transmission device.

Images