Multi-element compounded insulating oil and application thereof

Abstract

The application discloses a kind of multi-element compound insulating oil and application, belong to liquid insulating dielectric technical field.The multi-element compound insulating oil includes following component, 25# naphthenic mineral oil: 65vol.-%-75vol.%, soybean oil: 5vol.-%-10vol.%, lauryl acid isooctyl ester: 1vol.-%-5vol.%, lauryl acid ethyl hexyl ester: 10vol.-%-30vol.%, antioxidant: 0.4wt%-5wt%.The multi-element compound insulating oil described in the application has good high-temperature resistance and higher lightning impulse breakdown voltage, and lower kinematic viscosity, dielectric loss and pour point, more excellent environmental protection performance.

Description

Technical Field

[0001] This invention relates to the field of liquid insulating dielectric technology, and in particular to a multi-component compound insulating oil and its applications. Background Technology

[0002] Oil-paper insulating oil is the "heart" of a transformer, and high-performance insulating oil is crucial for ensuring the safe and stable operation of the transformer. Currently, there are three types of insulating oil used in transformers: mineral oil, natural esters, and synthetic esters. Among them, mineral insulating oil has a low flash point and ignition point, poor thermal stability, is prone to aging, and has a low ignition and explosion temperature, which seriously restricts the safe operation level and service life of transformers. Furthermore, it has poor biodegradability and is a non-renewable resource. Compared with mineral oil, natural esters have good physical, chemical, and electrical properties, and excel in renewability, fire resistance, and environmental friendliness, delaying the aging of insulating paperboard. However, natural esters have disadvantages such as high pour point, high viscosity, poor oxidation stability, high acid value and dielectric loss, and poor lightning impulse breakdown performance. Compared with mineral oil, synthetic ester insulating oil has superior electrical properties, but it is expensive and requires complex manufacturing equipment and technology. It also has higher viscosity, lower lightning impulse breakdown voltage, and poorer fire resistance and oxidation stability.

[0003] Compared to mineral oil, blended insulating oils (also known as compounded insulating oils) can complement the performance advantages of mineral oil and ester oils, representing an important direction for the development of new liquid dielectrics. Currently, the main performance parameters of traditional binary blended insulating oils (mixtures of mineral oil and natural esters, mineral oil and synthetic esters, and natural esters) do not meet the requirements of the current standard GB 2536-2011, "Unused Mineral Insulating Oils for Electrical Fluid Transformers and Switches." For example, in 2002, Professor I. Fofana and others from the University of Quebec first blended synthetic esters and mineral oils, determining the optimal ratio. In 2008, Indonesian scholars pioneered the mixing of natural esters and mineral oils, obtaining the variation patterns of parameters such as dielectric breakdown voltage, viscosity, and density with the mixing ratio. However, the dielectric loss and kinematic viscosity of the aforementioned binary blended insulating oils are still relatively high, failing to meet the requirements of the current standard IEC 60296:2012. Although the performance parameters of the ternary hybrid insulating oil (76% mineral oil + 19% soybean oil + 5% PFAE) meet the requirements of GB 2536-2011, its lightning impulse breakdown voltage is relatively low, and there is still room for further optimization of dielectric loss and viscosity. For example, in 2019, Chongqing University, focusing on the synergistic effect of different oil components, compounded and optimized mineral oil, soybean oil, and palm-based PFAE oil in different proportions, pioneering the development of a new type of ternary hybrid insulating oil both domestically and internationally. The basic performance parameters of this oil meet the requirements of current standards IEC60296:2012 and GB2536-2011. However, the negative polarity lightning impulse voltage of this ternary hybrid insulating oil is only 60% of that of mineral oil, and its dielectric loss and viscosity still have room for further improvement.

[0004] Therefore, researching and developing a new multi-component composite insulating oil that meets standard requirements and has resistance to high temperatures and strong electric fields is of great significance for the widespread application of composite insulating oils. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a multi-component composite insulating oil and its application. The multi-component composite insulating oil has higher lightning impulse breakdown voltage and flash point, and superior resistance to high temperature and strong electric field impact.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a multi-component composite insulating oil, comprising the following components:

[0008] 25# naphthenic mineral oil: 65 vol.% - 75 vol.%;

[0009] Soybean oil: 5 vol.% - 10 vol.%;

[0010] Isooctyl laurate: 1 vol.% - 5 vol.%;

[0011] Ethylhexyl laurate: 10 vol.% - 30 vol.%;

[0012] Antioxidant: 0.4wt%-5wt%.

[0013] The total volume content of the multi-component compound insulating oil, excluding the antioxidant, is 100 vol.%.

[0014] The antioxidant content is 0.4wt%-5wt% of the total mass of the multi-component compound insulating oil.

[0015] The synergistic effect of the above-mentioned 25# cycloalkyl mineral oil, soybean oil, isooctyl laurate and ethylhexyl laurate significantly improves the insulating oil's resistance to high temperature and strong electric field impact.

[0016] Preferably, the antioxidant is selected from phenolic antioxidants and amine antioxidants.

[0017] Preferably, the content of the phenolic antioxidant or amine antioxidant is 0.2wt%-2.5wt%;

[0018] Preferably, the phenolic antioxidant is selected from T511 or T501.

[0019] Preferably, the amine antioxidant is selected from L06 or L57.

[0020] The antioxidants mentioned above are specifically selected from T511 and L06, or T511 and L57, or T501 and L06, or T501 and L57.

[0021] More preferably, the multi-component composite insulating oil of the present invention comprises the following components:

[0022] 25# naphthenic mineral oil: 65 vol.% - 70 vol.%;

[0023] Soybean oil: 8 vol.% - 10 vol.%;

[0024] Isooctyl laurate: 3 vol.% - 5 vol.%;

[0025] Ethylhexyl laurate: 15 vol.% - 20 vol.%;

[0026] Antioxidant: 0.4wt%-2wt%.

[0027] In a further preferred embodiment of the present invention, the multi-component composite insulating oil comprises the following components:

[0028] 25# naphthenic mineral oil: 65 vol.%;

[0029] Soybean oil: 10 vol.%;

[0030] Isooctyl laurate: 5 vol.%;

[0031] Ethylhexyl laurate: 20 vol.%;

[0032] Antioxidant: 0.4 wt%.

[0033] In a further preferred embodiment of the present invention, the multi-component composite insulating oil comprises the following components:

[0034] 25# naphthenic mineral oil: 70 vol.%; soybean oil: 10 vol.%;

[0035] Isooctyl laurate: 5 vol.%;

[0036] Ethylhexyl laurate: 15 vol.%;

[0037] Antioxidant: 0.4 wt%.

[0038] In some specific embodiments of the present invention, the antioxidant is selected from T511 and L06.

[0039] The content of T511 is preferably 0.2 wt%.

[0040] The content of L06 is preferably 0.2 wt%.

[0041] This invention also provides the application of the above-mentioned multi-component insulating oil in electrical equipment.

[0042] Preferably, the electrical equipment includes, but is not limited to, oil-immersed transformers.

[0043] Compared with existing technologies, the multi-component compound insulating oil provided by this invention comprises the following components: 25# naphthenic mineral oil: 65 vol.%-75 vol.%, soybean oil: 5 vol.%-10 vol.%, isooctyl laurate: 1 vol.%-5 vol.%, ethylhexyl laurate: 10 vol.%-30 vol.%, and antioxidant: 0.4 wt%-5 wt%. The multi-component compound insulating oil of this invention exhibits excellent high-temperature resistance and a high lightning impulse breakdown voltage, while also having lower kinematic viscosity, dielectric loss, and pour point, and superior environmental performance. Attached Figure Description

[0044] Figure 1 The graphs show the specific heat capacity and thermal conductivity of the multi-component insulating oil and 25# naphthenic mineral oil in Example 1, where (a) is the specific heat capacity graph and (b) is the thermal conductivity graph.

[0045] Figure 2 The average lightning impulse breakdown voltages of multi-component insulating oil, 25# naphthenic mineral oil, ternary composite insulating oil, 80 vol.% 25# naphthenic mineral oil + 20 vol.% soybean oil, and soybean oil under negative polarity are plotted. Detailed Implementation

[0046] To further illustrate the present invention, the following detailed description of the multi-component insulating oil provided by the present invention and its applications is provided in conjunction with embodiments.

[0047] The 25# cycloalkyl mineral oil of this invention is a commercially available product, purchased from Chongqing Chuanrun Petrochemical Co., Ltd.

[0048] The soybean oil was purchased from Henan Jiuyu Enpai Electric Technology Co., Ltd. as NP natural ester insulating oil.

[0049] Example 1

[0050] A multi-component composite insulating oil was prepared by mixing 65 vol.% of 25# naphthenic mineral oil, 10 vol.% of soybean oil, 5 vol.% of isooctyl laurate, 20 vol.% of ethylhexyl laurate, 0.2 wt% of T511, and 0.2 wt% of L06.

[0051] Example 2

[0052] A multi-component composite insulating oil was prepared by mixing 70% of 25# naphthenic mineral oil, 10 vol.% of soybean oil, 5 vol.% of isooctyl laurate, 15 vol.% of ethylhexyl laurate, 0.2 wt% of T511 and 0.2 wt% of L06.

[0053] Comparative Example 1

[0054] A multi-component composite insulating oil was prepared by mixing 60 vol.% of 25# naphthenic mineral oil, 10 vol.% of soybean oil, 15 vol.% of isooctyl laurate, 15 vol.% of ethylhexyl laurate, 0.2 wt% of T511, and 0.2 wt% of L06.

[0055] Comparative Example 2

[0056] A multi-component composite insulating oil was prepared by mixing 60 vol.% of 25# naphthenic mineral oil, 10 vol.% of soybean oil, 5 vol.% of isooctyl laurate, 25 vol.% of ethylhexyl laurate, 0.2 wt% of T511 and 0.2 wt% of L06.

[0057] The acid value, dielectric loss, flash point and lightning impulse breakdown voltage of the multi-component insulating oils prepared in Examples 1-2 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0058] Table 1. Acid value, dielectric loss, flash point, and lightning impulse breakdown voltage of multi-component insulating oils with different proportions.

[0059]

[0060] As shown in Table 2, the acid value and dielectric loss of the multi-component composite insulating oils in Comparative Examples 1 and 2 do not meet the GB2536-2011 standard. The acid value and dielectric loss of the multi-component composite insulating oils in Examples 1, 2, and 3 all meet the standard, and their lightning impulse breakdown voltages are also higher than those in Comparative Examples 1 and 2.

[0061] Comparative Example 3

[0062] A ternary composite insulating oil was prepared by mixing 76 vol.% of 25# naphthenic mineral oil, 19 vol.% of soybean oil, and 5 vol.% of ethylhexyl laurate.

[0063] Comparative Example 4

[0064] A binary composite insulating oil was prepared by mixing 80 vol.% 25# cycloalkyl mineral oil and 20 vol.% rapeseed oil.

[0065] The performance of the multi-component insulating oil and 25# naphthenic mineral oil prepared in Example 1 and Comparative Examples 3-4 was tested, specifically for their physical, chemical and electrical properties, heat dissipation performance, negative polarity lightning impulse breakdown voltage, and environmental performance.

[0066] (1) Physical, chemical and electrical performance testing

[0067] The physicochemical and electrical properties of the multi-component insulating oils prepared in Example 1 and Comparative Examples 3-4, as well as 25# cycloalkyl mineral oil, were tested and the results are shown in Table 2. Table 2 compares the physicochemical and electrical property parameters of the insulating oils under high temperature and strong impact field conditions.

[0068] Table 2. Performance parameters of insulating oils under high temperature and impact field conditions.

[0069]

[0070]

[0071] Table 2 shows that the performance parameters of the multi-component composite insulating oil described in this invention meet GB2536-2011, and its key physicochemical and electrical properties are superior to those of 25# naphthenic mineral oil. Specifically, compared with 25# naphthenic mineral oil, the multi-component composite insulating oil described in this invention (Example 1) has a lower viscosity, and its pour point is 22°C lower than that of 25# naphthenic mineral oil, enabling safer operation in cold regions. Furthermore, the power frequency breakdown voltage of the multi-component composite insulating oil is 20.9kV higher than that of 25# naphthenic mineral oil, and its flash point is 19°C higher, indicating that the multi-component composite insulating oil described in this invention has superior insulation and high-temperature resistance.

[0072] The multi-component compound insulating oil of the present invention (Example 1) has a higher lightning impulse breakdown voltage and flash point than the insulating oils prepared in Comparative Examples 3 and 4, and the dielectric loss of the insulating oil in Comparative Example 4 does not meet the requirements of GB2536-2011 standard.

[0073] (2) Heat dissipation performance test

[0074] This invention, based on ASTM E1461 "Determination of Thermal Diffusivity by Flash Method", uses differential scanning calorimetry to determine the specific heat capacity of multi-component composite insulating oil (Example 1) and 25# naphthenic mineral oil. The results are as follows: Figure 1 As shown.

[0075] The results show that the specific heat capacity and thermal conductivity of both the multi-component composite insulating oil and 25# naphthenic mineral oil increase linearly with increasing temperature. Compared with 25# naphthenic mineral oil, the multi-component composite insulating oil of Example 1 has higher specific heat capacity and thermal conductivity at any temperature, but the difference in specific heat capacity and thermal conductivity decreases with increasing temperature. At 30℃, the specific heat capacity and thermal conductivity of the multi-component composite insulating oil are 59.02% and 74.19% higher than those of 25# naphthenic mineral oil, respectively. When the temperature reaches 110℃, the specific heat capacity and thermal conductivity of the multi-component composite insulating oil are 14.21% and 36.51% higher than those of 25# naphthenic mineral oil, respectively. The operating temperature of transformers is generally between 40℃ and 90℃. Within this temperature range, the specific heat capacity and thermal conductivity of the multi-component composite insulating oil are both higher than those of 25# naphthenic mineral oil, indicating that the heat dissipation capacity of the multi-component composite insulating oil is superior to that of 25# naphthenic mineral oil.

[0076] (3) Test of negative polarity lightning impulse breakdown voltage

[0077] Under negative polarity conditions, the lightning impulse breakdown voltages of the above-mentioned multi-component composite insulating oil (Example 1), 25# naphthenic mineral oil, ternary composite insulating oil (Comparative Example 3), and binary composite insulating oil (Comparative Example 4) were tested. Figure 2As shown. The results show that, under any gap, the average lightning impulse breakdown voltage of the multi-component composite insulating oil of the present invention is significantly higher than that of the existing binary composite insulating oil (Comparative Example 4) and ternary composite insulating oil (Comparative Example 3); when the oil gap is 105 mm, the average lightning impulse breakdown voltage of the multi-component composite insulating oil is comparable to that of 25# naphthenic mineral oil, and it has the technical advantage of withstanding strong field impulse voltage.

[0078] (4) Environmental performance test

[0079] The ester content in the multi-component composite insulating oil (Example 1) ranges from 25 vol.% to 35 vol.%, and its biodegradability is higher than that of the binary composite insulating oil (Comparative Example 4) and ternary composite insulating oil (Comparative Example 3), and far higher than that of 25# naphthenic mineral oil. This demonstrates that the multi-component composite insulating oil described in this invention has outstanding advantages in environmental performance.

[0080] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A multi-component composite insulating oil, characterized in that, Includes the following ingredients: 25# Naphthenic Mineral Oil: 65 vol.%-75 vol.%; Soybean oil: 5 vol.% - 10 vol.%; Isooctyl laurate: 1 vol.% - 5 vol.%; Ethylhexyl laurate: 10 vol.% - 30 vol.%; Antioxidant: 0.4 wt%-5 wt%; The total volume content of the multi-component compound insulating oil, excluding the antioxidant, is 100 vol.%. The antioxidant content is 0.4 wt%-5 wt% of the total mass of the multi-component compound insulating oil.

2. The multi-component composite insulating oil according to claim 1, characterized in that, The antioxidants are selected from phenolic antioxidants and amine antioxidants; The content of the phenolic antioxidant or amine antioxidant is 0.2 wt%-2.5 wt% of the total mass of the multi-component compound insulating oil; The phenolic antioxidant is selected from T511 or T501; The amine antioxidant is selected from L06 or L57.

3. The multi-component composite insulating oil according to claim 1, characterized in that, The multi-component composite insulating oil includes the following components: 25# Naphthenic Mineral Oil: 65 vol.%-70 vol.%; Soybean oil: 8 vol.%-10 vol.%; Isooctyl laurate: 3 vol.% - 5 vol.%; Ethylhexyl laurate: 15 vol.%-20 vol.%; Antioxidants: 0.4 wt%-2 wt%; The antioxidant content is 0.4 wt%-2 wt% of the total mass of the multi-component compound insulating oil.

4. The multi-component composite insulating oil according to claim 1, characterized in that, The multi-component composite insulating oil includes the following components: 25# Naphthenic Mineral Oil: 65 vol.% Soybean oil: 10 vol.%; Isooctyl laurate: 5 vol.% Ethylhexyl laurate: 20 vol.% Antioxidant: 0.4 wt% The antioxidant content is 0.4 wt% of the total mass of the multi-component compound insulating oil.

5. The multi-component composite insulating oil according to claim 1, characterized in that, The multi-component composite insulating oil includes the following components: 25# naphthenic mineral oil: 70 vol.%; soybean oil: 10 vol.%; Isooctyl laurate: 5 vol.% Ethylhexyl laurate: 15 vol.% Antioxidant: 0.4 wt% The antioxidant content is 0.4 wt% of the total mass of the multi-component compound insulating oil.

6. The application of the multi-component insulating oil according to any one of claims 1 to 5 in electrical equipment.

7. The application according to claim 6, characterized in that, The electrical equipment is selected from oil-immersed transformers.

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