Compound additive and application thereof in removing corrosive sulfur products in mineral insulating oil

Abstract

The invention discloses a compound additive and application thereof in removing corrosive sulfur products in mineral insulating oil, and relates to the field of insulating oil additives. Comprising a first inhibitor, a second inhibitor, a first antioxidant and a second antioxidant, the first inhibitor is a benzotriazole derivative, and the second inhibitor is a thiadiazole derivative and / or methyl benzotriazole; the first antioxidant is pyrogallic acid, and the second antioxidant is butylated hydroxytoluene and / or tert-butylhydroquinone. According to the additive, the compound inhibitor and the compound antioxidant are adopted, when the additive is applied to the field of mineral insulating oil, the corrosion and sulfur resistance of the insulating oil is improved through the synergistic interaction effect of the compound inhibitor, and meanwhile the oxidation resistance of the insulating oil is improved to the maximum extent through mutual balance of the compound antioxidant and the compound inhibitor; and continuous and efficient protection is provided for the mineral insulating oil in actual operation, so that the physical property and the electrical property of the mineral insulating oil are excellent.

Description

Technical Field

[0001] The invention relates to the field of insulating oil additives, in particular to a compound additive and application thereof in removing corrosive sulfur products in mineral insulating oil. Background Art

[0002] At present, the insulating oil used in oil-immersed transformers is mainly divided into mineral insulating oil and ester-based insulating oil. Among them, the phenomenon of insulation failure caused by the degradation of the insulation performance of transformers and reactors due to the corrosive sulfur contained in mineral insulating oil has attracted widespread attention. Corrosive sulfur refers to sulfur elements or unstable sulfides that can react with metals to form metal sulfides under certain conditions. They are highly corrosive to metals. Corrosive sulfur mainly includes elemental sulfur, hydrogen sulfide, mercaptan and some small molecular sulfides. They react with copper metal to form light blue and dark gray sediments (cuprous sulfide). This substance is a semi-conductive substance that penetrates into the oil-paper insulation system to cause insulation breakdown, thereby reducing the insulation performance of the transformer and greatly affecting the safe and stable operation of the transformer.

[0003] At present, the methods for removing corrosive sulfur in mineral oil mainly include replacing new oil, filtering oil and adding inhibitors. Among them, the method of adding inhibitors is relatively economical and effective, and has been widely used to remove corrosive sulfur in mineral insulating oil. Common inhibitors include T551, T561, TTA, BTA, etc. The above inhibitors are all benzotriazole and its derivatives, and their inhibition mechanism is a film-forming reaction mechanism. The side chain connected to the nitrogen atom on the benzotriazole ring will break during the reaction process, and the nitrogen atom chelates with copper to form a benzotriazole-copper coordination compound. The film can protect the copper winding from being corroded by the corrosive sulfur in the oil.

[0004] However, while the inhibitor removes the corrosive sulfur in mineral oil, it also affects the anti-oxidation property of the mineral oil itself, thus reducing the service life of the mineral oil. It is urgent to seek a technology that can balance the corrosive sulfur content in mineral oil while ensuring the anti-oxidation ability for industrial application. Summary of the invention

[0005] The present invention provides a compound additive and its application in removing corrosive sulfur products in mineral insulating oil. By adopting a compound inhibitor and a compound antioxidant, when added to the mineral insulating oil, the anti-corrosive sulfur ability and antioxidant ability of the insulating oil can be maximized, providing continuous and efficient protection for the mineral insulating oil in actual operation.

[0006] In order to solve the above technical problems, one of the purposes of the present invention is to provide a compound additive, including an inhibitor and an antioxidant, the inhibitor including a first inhibitor and a second inhibitor, the first inhibitor is a benzotriazole derivative, and the second inhibitor is a thiadiazole derivative and / or methylbenzotriazole; the antioxidant includes a first antioxidant and a second antioxidant, the first antioxidant is pyrogallic acid, and the second antioxidant is dibutylhydroxytoluene and / or tert-butylhydroquinone; the mass fraction of the first inhibitor in the compound additive accounts for more than 40wt%, and the mass fraction of the first antioxidant in the compound additive accounts for more than 20wt%.

[0007] By adopting the above scheme, the present application aims at the problem of reduced oxidation resistance and shortened service life of mineral oil in previous studies on sulfur removal inhibitors for mineral insulating oil. The additive adopts a compound inhibitor and a compound antioxidant, wherein the smaller the dissociation energy of the pyrogallic acid antioxidant is, the stronger the antioxidant activity is, the larger the number of effective phenolic hydroxyl groups per unit mass is, and the higher the DPPH removal rate is. The benzotriazole derivative inhibitor has strong sulfur corrosion resistance and low antioxidant effect on insulating oil. When applied to the field of mineral insulating oil, the synergistic effect of the compound inhibitor is used to improve the sulfur corrosion resistance of the insulating oil. The side chain connected to the nitrogen atom on the benzotriazole ring of the inhibitor is broken during the reaction process, and the nitrogen atom chelates with the metal to form a benzotriazole-metal coordination compound. The film formation can protect the metal from being corroded by the corrosive sulfur in the oil. At the same time, the compound antioxidant and the compound inhibitor are balanced with each other to maximize the antioxidant capacity of the insulating oil, which has a good effect on improving the physical properties and electrical properties of the mineral insulating oil, provides continuous and efficient protection for the mineral insulating oil in actual operation, and has excellent comprehensive performance.

[0008] As a preferred solution, the mass fraction of the first inhibitor in the compound additive is 40wt%-50wt%, and the mass fraction of the first antioxidant in the compound additive is 20wt%-25wt%.

[0009] As a preferred embodiment, the inhibitor and the antioxidant are included in a mass ratio of (3-5):(2-3).

[0010] By adopting the above scheme, the present application controls the addition ratio of inhibitors and antioxidants, which can maximize the anti-corrosion sulfur ability and anti-oxidation ability of the insulating oil, avoid the inhibitor affecting the antioxidant ability of the insulating oil, and at the same time ensure that the insulating oil has excellent anti-corrosion sulfur ability and excellent comprehensive performance.

[0011] As a preferred embodiment, the first inhibitor, the second inhibitor, the first antioxidant and the second antioxidant are included in a mass ratio of (2-4):1:(1-2):1.

[0012] As a preferred embodiment, the mass ratio of the first inhibitor, the second inhibitor, the first antioxidant and the second antioxidant is 4:1:2:1.

[0013] As a preferred embodiment, the second inhibitor is methylbenzotriazole, and the second antioxidant is butylated hydroxytoluene.

[0014] In order to solve the above technical problems, a second object of the present invention is to provide an application of a composite additive in removing corrosive sulfur products from mineral insulating oil.

[0015] In order to solve the above technical problems, the third object of the present invention is to provide a mineral insulating oil with good anti-corrosive sulfur performance, including a compound additive with a mass fraction of 0.1wt%-1wt%.

[0016] As a preferred embodiment, the invention further comprises 90wt%-99.9wt% of a mineral oil matrix and 1wt%-9wt% of a functional auxiliary agent, wherein the functional auxiliary agent is at least one of a preservative, an antifoaming agent, an anti-emulsifier and a detergent.

[0017] As a preferred embodiment, the mineral oil matrix is ​​Xinjiang Karamay No. 25 mineral oil.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The additive of the present application adopts a compound inhibitor and a compound antioxidant. When applied to the field of mineral insulating oil, the synergistic effect of the compound inhibitor is used to improve the corrosion resistance of the insulating oil to sulfur. The side chain connected to the nitrogen atom on the benzotriazole ring of the inhibitor is broken during the reaction process, and the nitrogen atom chelates with the metal to form a benzotriazole-metal coordination compound. The film formation plays a role in protecting the metal from being corroded by the corrosive sulfur in the oil. At the same time, the compound antioxidant and the compound inhibitor are balanced with each other to maximize the antioxidant capacity of the insulating oil, thereby providing continuous and efficient protection for the mineral insulating oil in actual operation. DETAILED DESCRIPTION

[0020] 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.

[0021] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0022] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0023] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0024] The terms "include", "comprising", "having", "containing", etc. used herein are open-ended terms, which mean including but not limited to. Unless otherwise specified, all raw materials used can be obtained from commercial sources, and the same raw materials are used in parallel experiments.

[0025] Example 1

[0026] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and a thiadiazole derivative (T561), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising a benzotriazole derivative (T551), a thiadiazole derivative (T561), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 4:1:2:1.

[0027] Example 2

[0028] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ), specifically comprising a benzotriazole derivative (T551), methylbenzotriazole (TTA), pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ) in a mass ratio of 4:1:2:1.

[0029] Example 3

[0030] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and a thiadiazole derivative (T561), and the antioxidant is pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ), specifically comprising a benzotriazole derivative (T551), a thiadiazole derivative (T561), pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ) in a mass ratio of 4:1:2:1.

[0031] Example 4

[0032] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising a benzotriazole derivative (T551), methylbenzotriazole (TTA), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 4:1:2:1.

[0033] Example 5

[0034] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and a thiadiazole derivative (T561), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising a benzotriazole derivative (T551), a thiadiazole derivative (T561), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 2:1:1:1.

[0035] Example 6

[0036] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ), specifically comprising a benzotriazole derivative (T551), methylbenzotriazole (TTA), pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ) in a mass ratio of 2:1:1:1.

[0037] Example 7

[0038] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and a thiadiazole derivative (T561), and the antioxidant is pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ), specifically comprising a benzotriazole derivative (T551), a thiadiazole derivative (T561), pyrogallic acid (PY) and tert-butylhydroquinone (TBHQ) in a mass ratio of 2:1:1:1.

[0039] Example 8

[0040] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising a benzotriazole derivative (T551), methylbenzotriazole (TTA), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 2:1:1:1.

[0041] Comparative Example 1

[0042] A compound additive comprises an inhibitor and an antioxidant in a mass ratio of 3:2, wherein the inhibitor is a benzotriazole derivative (T551) and the antioxidant is pyrogallic acid (PY).

[0043] Comparative Example 2

[0044] A compound additive comprises an inhibitor and an antioxidant in a mass ratio of 5:3, wherein the inhibitor is a benzotriazole derivative (T551) and the antioxidant is pyrogallic acid (PY).

[0045] Comparative Example 3

[0046] An additive includes an inhibitor, wherein the inhibitor is a benzotriazole derivative (T551).

[0047] Comparative Example 4

[0048] An additive includes an inhibitor, wherein the inhibitor is a thiadiazole derivative (T561).

[0049] Comparative Example 5

[0050] An additive includes an inhibitor, wherein the inhibitor is methyl benzotriazole (TAA).

[0051] Comparative Example 6

[0052] An additive includes an antioxidant, wherein the antioxidant is pyrogallic acid (PY).

[0053] Comparative Example 7

[0054] An additive includes an antioxidant, wherein the antioxidant is butylated hydroxytoluene (BHT).

[0055] Comparative Example 8

[0056] An additive comprises an antioxidant, wherein the antioxidant is tert-butylhydroquinone (TBHQ).

[0057] Comparative Example 9

[0058] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is 2,6-di-tert-butyl-p-cresol (DBPC) and tolyltriazole (TAA), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising 2,6-di-tert-butyl-p-cresol (DBPC), tolyltriazole (TTA), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 2:1:1:1.

[0059] Comparative Example 10

[0060] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is 1,2,3-benzotriazole (BTA) and tolyltriazole (TAA), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising 1,2,3-benzotriazole (BTA), tolyltriazole (TTA), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 2:1:1:1.

[0061] Comparative Example 11

[0062] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is 2,6-di-tert-butyl-p-cresol (T501) and butylated hydroxytoluene (BHT), specifically comprising the benzotriazole derivative (T551), methylbenzotriazole (TTA), 2,6-di-tert-butyl-p-cresol (T501) and butylated hydroxytoluene (BHT) in a mass ratio of 2:1:1:1.

[0063] Comparative Example 12

[0064] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (1076) and butylated hydroxytoluene (BHT), specifically comprising the benzotriazole derivative (T551), methylbenzotriazole (TTA), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (1076) and butylated hydroxytoluene (BHT) in a mass ratio of 2:1:1:1.

[0065] Comparative Example 13

[0066] A compound additive comprises an inhibitor and an antioxidant, wherein the inhibitor is a benzotriazole derivative (T551) and methylbenzotriazole (TAA), and the antioxidant is pyrogallic acid (PY) and butylated hydroxytoluene (BHT), specifically comprising a benzotriazole derivative (T551), methylbenzotriazole (TTA), pyrogallic acid (PY) and butylated hydroxytoluene (BHT) in a mass ratio of 8:2:2:1.

[0067] Application Examples 1-8 and Comparative Application Examples 1-12

[0068] The application of a compound additive in removing corrosive sulfur products from mineral insulating oil comprises the following steps:

[0069] Add 0.8% by mass of the additives of Example 1-8 or Comparative Example 1-12 to the mineral insulating oil, where the mineral insulating oil is Xinjiang Karamay No. 25 mineral oil. Use a small or medium-sized elliptical stirring bar to place the oil sample on a magnetic stirrer and stir it for 6 hours at room temperature to ensure that the solid particles of the compound additive are fully dissolved in the oil sample. After the dissolution is completed, the oil sample is clear and free of suspension, and the color is slightly deepened.

[0070] Comparative Application Example 13

[0071] The invention discloses an application of a compound additive in removing corrosive sulfur products from synthetic ester insulating oil, comprising the following steps:

[0072] Add 0.8% by mass of the additive of Example 4 to the synthetic ester insulating oil, Midel 7131 is selected as the synthetic ester insulating oil, and the oil sample is placed on a magnetic stirrer and stirred for 6 hours using a small or medium-sized elliptical stirring bar at room temperature to ensure that the solid particles of the compound additive are fully dissolved in the oil sample. After the dissolution is completed, the oil sample is clear without suspension, and the color is slightly deepened.

[0073] Comparative Application Example 14

[0074] The invention discloses an application of a compound additive in removing corrosive sulfur products from natural ester insulating oil, comprising the following steps:

[0075] The additive of Example 4 was added in a mass fraction of 0.8% to the natural ester insulating oil. FR3 was selected as the natural ester insulating oil. The oil sample was placed on a magnetic stirrer and stirred for 6 hours using a small or medium-sized elliptical stirring bar at room temperature to ensure that the solid particles of the compound additive were fully dissolved in the oil sample. After the dissolution was completed, the oil sample was clear without suspension and the color was slightly deepened.

[0076] Comparative Application Example 15

[0077] The invention discloses an application of a compound additive in removing corrosive sulfur products from mineral insulating oil, comprising the following steps:

[0078] Add the additive of Example 13 in a mass fraction of 1.3% to the mineral insulating oil. The mineral insulating oil is Xinjiang Karamay No. 25 mineral oil. Use a small or medium-sized elliptical stirring bar to place the oil sample on a magnetic stirrer and stir it for 6 hours at room temperature to ensure that the solid particles of the compound additive are fully dissolved in the oil sample. After the dissolution is completed, the oil sample is clear and free of suspension, and the color is slightly deepened.

[0079] Performance testing

[0080] 1. Use mineral insulating oil, natural ester insulating oil and synthetic ester insulating oil without additives as blank insulating oil samples, and use the treated oil samples of application examples and comparative application examples as test oil samples.

[0081] 2536--2011 "Unused mineral insulating oil for electrical fluid transformers and switches" standard, using SH / T0804 electrical insulating oil corrosive sulfur test silver sheet test method, the treated silver sheet is kept in 100 ° C insulating oil for 18 hours, after the experiment is over, the potential corrosive sulfur in the tested oil sample is determined by observing the surface changes of the silver sheet. The determination method is shown in Table 1 below. The effects of different additives in the embodiments and comparative examples on removing corrosive sulfur from insulating oil are compared, and the test results are shown in Table 2 below.

[0082] Table 1 - Criteria for judging the corrosiveness of silver flakes in the silver flake test method

[0083]

[0084] Table 2 - Silver flake test results of insulating oil in the application examples of this application and the comparative application examples

[0085]

[0086]

[0087]

[0088] 2. Mineral insulating oil without additives was used as a blank insulating oil sample, and the oil samples after treatment of the application example and the comparative application example were used as test oil samples. According to DL / T 1977-2019 "Determination of Oxidation Stability of Mineral Insulating Oil - Differential Scanning Calorimetry", the initial oxidation temperature of the oil sample was measured; according to the method of GB / T 7595-2008 "Quality Standard for Transformer Oil in Operation", the oil sample was sealed in a forced air drying oven for a 15-day oxidation experiment. The experimental temperature was set to 180°C. The acid value, viscosity and 90°C dielectric loss of the oil sample after the oxidation experiment were tested. The test results are shown in Table 3 below.

[0089] Table 3 - Oxidation test results of insulating oil in the application examples of this application and the comparative application examples

[0090]

[0091]

[0092] As shown in Table 1-2, by comparing Application Examples 1-4 with Comparative Application Example 2 and Application Examples 5-8 with Comparative Application Example 1, it can be seen that when Application Example 1-8 uses a compound inhibitor and a compound antioxidant to add to the insulating oil, the insulating oil has a high anti-corrosive sulfur ability, no discoloration occurs in the silver sheet test, and after the oxidation test, the insulating oil has a higher initial oxidation temperature, a lower acid value, and lower dielectric loss and viscosity than the blank mineral insulating oil, indicating that the insulating oil has excellent antioxidant properties; while Comparative Application Example 1-2 uses a single inhibitor and a single antioxidant to add to the insulating oil, and the silver sheet test shows obvious golden yellow discoloration, indicating that the insulating oil has insufficient anti-corrosive sulfur ability, and after the oxidation test, the insulating oil has a lower initial oxidation temperature than Application Example 1-8, the acid value of Comparative Application Example 1 increases, and the dielectric loss is lower than that of Application Example 1-8, indicating that the insulating oil of Comparative Application Example 1-2 has an inferior antioxidant capacity.

[0093] As shown in Table 1-2, by comparing Application Examples 1-8 with Comparative Application Examples 3-5 and Comparative Application Examples 6-8, it can be found that in Comparative Application Example 3-5, only a single inhibitor is added, resulting in insufficient anti-corrosive sulfur resistance of the insulating oil, a golden yellow discoloration in the silver sheet test, and no antioxidant is added. The inhibitor will reduce the antioxidant capacity of the insulating oil itself, resulting in lower antioxidant capacity of the insulating oil than the blank insulating oil, lower initial oxidation temperature, higher acid value, higher dielectric loss and viscosity. Comparative Application Example 6-8 does not add an inhibitor, the insulating oil's anti-corrosive sulfur resistance is significantly poor, the proportion of antioxidants in the insulating oil is increased, and the insulating oil has better antioxidant capacity.

[0094] As shown in Table 1-2, by comparing Application Example 8 with Comparative Application Examples 9-10 and Comparative Application Examples 11-12, it can be seen that the inhibitor T551 in Comparative Application Examples 9-10 is replaced in equal amounts with other inhibitors such as DBPC or BTA, and it is found that the silver sheet test shows an obvious golden yellow discoloration, indicating that the anti-corrosive sulfur ability is reduced, indicating that the addition of inhibitor T551 can effectively improve the anti-corrosive sulfur ability of the insulating oil compared with other inhibitors; the antioxidant PY in Comparative Application Examples 11-12 is replaced in equal amounts with other antioxidants such as T501 or 1076, and it is found that the antioxidant ability of the insulating oil is reduced, indicating that the antioxidant PY used in this application is better than other antioxidants.

[0095] As shown in Table 1-2, by comparing Application Example 4 and Comparative Application Example 15, it can be seen that the total amount of the inhibitor in the insulating oil of Comparative Application Example 15 is larger than that of Application Example 14. The antioxidant content is the same, and the total amount of inhibitors increases, resulting in a decrease in the antioxidant capacity of the insulating oil, a decrease in the initial oxidation temperature, and an increase in the acid value and dielectric loss, indicating that the content of the inhibitor will affect the antioxidant capacity of the insulating oil. The present application controls the addition ratio of the inhibitor and the antioxidant, which can maximize the corrosion resistance and antioxidant capacity of the insulating oil, and has excellent comprehensive performance.

[0096] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A compound additive, characterized in that: The invention comprises an inhibitor and an antioxidant, wherein the inhibitor comprises a first inhibitor and a second inhibitor, wherein the first inhibitor is a benzotriazole derivative, and the second inhibitor is a thiadiazole derivative and / or methylbenzotriazole; the antioxidant comprises a first antioxidant and a second antioxidant, wherein the first antioxidant is pyrogallic acid, and the second antioxidant is butylated hydroxytoluene and / or tert-butylhydroquinone; the mass fraction of the first inhibitor in the compound additive accounts for more than 40wt%, and the mass fraction of the first antioxidant in the compound additive accounts for more than 20wt%.

2. The compound additive according to claim 1, characterized in that: The mass fraction of the first inhibitor in the compound additive is 40wt%-50wt%, and the mass fraction of the first antioxidant in the compound additive is 20wt%-25wt%.

3. The compound additive according to claim 1, characterized in that: It includes an inhibitor and an antioxidant in a mass ratio of (3-5):(2-3).

4. The compound additive according to claim 1, characterized in that: The invention comprises a first inhibitor, a second inhibitor, a first antioxidant and a second antioxidant in a mass ratio of (2-4):1:(1-2):

1.

5. The compound additive according to claim 1, characterized in that: The mass ratio of the first inhibitor, the second inhibitor, the first antioxidant and the second antioxidant is 4:1:2:

1.

6. The compound additive according to claim 1, characterized in that: The second inhibitor is methylbenzotriazole, and the second antioxidant is butylated hydroxytoluene.

7. Use of the compound additive according to any one of claims 1 to 6 in removing corrosive sulfur products from mineral insulating oil.

8. A mineral insulating oil having good anti-corrosive sulfur performance, characterized in that: The invention comprises 0.1wt%-1wt% of the compound additive according to any one of claims 1 to 6.

9. A mineral insulating oil with good anti-corrosive sulfur performance as claimed in claim 8, characterized in that: The invention also comprises 90wt%-99.9wt% of a mineral oil matrix and 1wt%-9wt% of a functional auxiliary agent, wherein the functional auxiliary agent is at least one of a preservative, an antifoaming agent, an anti-emulsifier and a detergent.

10. A mineral insulating oil with good anti-corrosive sulfur performance as claimed in claim 9, characterized in that: The mineral oil matrix is ​​Xinjiang Karamay No. 25 mineral oil.

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