阅读说明：本技术 一种抗氧化菜籽绝缘油的制备方法 (Preparation method of antioxidant rapeseed insulating oil ) 是由 刘捷丰 张镱议 邢中玉 范贤浩 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种抗氧化菜籽绝缘油的制备方法,包括以下步骤：将菜籽绝缘油进行预处理,然后加入菜籽绝缘油重量的1～5%改性纳米氧化铝,超声振荡,得到抗氧化菜籽绝缘油；改性纳米氧化铝由以下步骤制备而成：在硝酸铝溶液中加入硝酸铝干重的0.5～2.0%由柠檬酸钠、聚乙烯吡咯烷酮和二辛基磺化琥珀酸钠组成的晶型控制剂,搅拌混合均匀得到混合溶液；向混合溶液中滴加氨水,直至混合溶液PH为8.0～9.5,搅拌反应,得到前驱体沉淀物,然后煅烧得到纳米粉末；对纳米粉末进行表面改性得到改性纳米氧化铝。本发明的方法中,采用纳米氧化铝粒子改性菜籽绝缘油,在保证电气绝缘性能的前提下可以增强其抗氧化性。(The invention discloses a preparation method of antioxidant rapeseed insulating oil, which comprises the following steps: pretreating the rapeseed insulating oil, adding modified nano alumina accounting for 1-5% of the weight of the rapeseed insulating oil, and performing ultrasonic oscillation to obtain antioxidant rapeseed insulating oil; the modified nano-alumina is prepared by the following steps: adding a crystal form control agent which is 0.5-2.0% of the dry weight of the aluminum nitrate and consists of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate into an aluminum nitrate solution, and uniformly stirring and mixing to obtain a mixed solution; dropwise adding ammonia water into the mixed solution until the pH value of the mixed solution is 8.0-9.5, stirring for reaction to obtain a precursor precipitate, and then calcining to obtain nano powder; and carrying out surface modification on the nano powder to obtain the modified nano aluminum oxide. In the method, the nanometer alumina particles are adopted to modify the rapeseed insulating oil, so that the oxidation resistance of the rapeseed insulating oil can be enhanced on the premise of ensuring the electrical insulating property.)

1. The preparation method of the antioxidant rapeseed insulating oil is characterized by comprising the following steps:

(1) carrying out vacuum drying on the rapeseed insulating oil, then heating the rapeseed insulating oil to 50-60 ℃, and mechanically stirring to obtain pretreated rapeseed insulating oil;

(2) adding modified nano alumina into the pretreated rapeseed insulating oil obtained in the step (1), wherein the addition amount of the modified nano alumina is 1-5% of the weight of the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation to obtain antioxidant rapeseed insulating oil;

the modified nano-alumina is prepared by the following steps:

s1, adding a crystal form control agent which is 0.5-2.0% of the dry weight of aluminum nitrate into an aluminum nitrate solution, and uniformly stirring and mixing to obtain a mixed solution, wherein the crystal form control agent is composed of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate;

s2, dropwise adding ammonia water into the mixed solution prepared in the step S1 under a stirring state until the pH value of the mixed solution is 8.0-9.5, stirring and reacting for 30-60 min, aging for 12-24 h, filtering to obtain a filter cake, and washing and drying the filter cake to obtain a precursor precipitate;

s3, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 8-10 ℃/min, the temperature is 1000-1200 ℃, and the time is 2-3 h;

and S4, mixing the nano-alumina powder obtained in the step S3 with deionized water to obtain a nano-alumina suspension, adding a surface modifier into the nano-alumina suspension, performing ultrasonic oscillation, and then filtering, washing and drying to obtain the modified nano-alumina.

2. The method according to claim 1, wherein the rapeseed insulating oleic acid has an acid value of 0.01 to 0.03mgKOH/g, a flash point at a closed end of 260 to 270 ℃, and a breakdown voltage of 70 to 80 kV.

3. The preparation method according to claim 1, wherein in the step (1), the mechanical stirring process parameters are as follows: the stirring speed is 250-300 r/min, and the stirring time is 30-60 min; in the step (2), the ultrasonic oscillation process parameters are as follows: the ultrasonic oscillation power is 1000-1200W, and the time is 30-60 min.

4. The preparation method according to claim 1, wherein the mass ratio of the sodium citrate to the polyvinylpyrrolidone to the dioctyl sodium sulfosuccinate in the crystal form control agent is 2-3: 1-2: 3-5.

5. The method according to claim 1, wherein the concentration of the aluminum nitrate solution is 0.5 to 2.0mol/L, and the concentration of the aqueous ammonia is 15 to 25% by volume.

6. The preparation method according to claim 1, wherein the nano-suspension has a solid content of 10 to 25%.

7. The preparation method of claim 1, wherein the surface modifier comprises polyethylene glycol, sodium laureth sulfate and a silane coupling agent, and the mass ratio of the polyethylene glycol to the sodium laureth sulfate to the silane coupling agent in the surface modifier is 1-3: 2-5: 3-7.

8. The preparation method according to claim 7, wherein the amount of the surface modifier added is 0.8 to 2.5% of the dry weight of the nano alumina in the nano alumina suspension.

9. The method as claimed in claim 1, wherein in step S2, the drying process is: drying for 0.5-1 h at 60-80 ℃ by microwave.

Technical Field

The invention belongs to the technical field of high-voltage electricity and insulating materials, and particularly relates to a preparation method of antioxidant rapeseed insulating oil.

Background

The oil-immersed transformer is a key device of a power system, and the failure of the oil-immersed transformer can cause power failure and great economic loss. The insulation performance of oil-filled transformers is mainly determined by the internal insulation consisting of insulating oil and insulating paper. The insulating oil plays roles of insulation, heat dissipation and cooling, and the guarantee of good operation characteristics of the insulating oil is very important for safe operation of the transformer. At present, the commonly used insulating oil is mineral insulating oil which is derived from petroleum products and is a non-renewable resource, and meanwhile, the biodegradation rate of the mineral insulating oil is lower than 30 percent, and once leakage occurs, the mineral insulating oil pollutes soil and water sources. In order to solve the increasingly important environmental protection problem and meet the requirement of sustainable development, a green and environment-friendly renewable insulating liquid dielectric body has become a new research subject.

The rapeseed oil has good electrical properties, and reaches or even exceeds the level of mineral insulating oil in the properties of power frequency breakdown voltage, relative dielectric constant and the like; the biodegradability is good, the biodegradation rate is more than 97%, and the environment-friendly property is achieved; also has high ignition point and low toxicity; the rapeseed insulating oil is used as transformer insulating oil, so that the pollution problem of the mineral insulating oil is solved, and the sustainable development requirement is met. However, during long-term operation, rapeseed insulating oils are more susceptible to oxidation than conventional mineral insulating oils, resulting in a reduction in their insulating properties. The development of the rapeseed insulating oil with high oxidation resistance has important significance for the stable operation of the transformer.

Disclosure of Invention

The invention aims to provide a preparation method of antioxidant rapeseed insulating oil, which improves the antioxidant capacity of the rapeseed insulating oil and delays the reduction rate of the insulating property of the rapeseed insulating oil caused by oxidation.

In order to achieve the above purpose, the invention is realized by the following technical scheme:

a preparation method of antioxidant rapeseed insulating oil comprises the following steps:

(1) carrying out vacuum drying on the rapeseed insulating oil, then heating the rapeseed insulating oil to 50-60 ℃, and mechanically stirring to obtain pretreated rapeseed insulating oil;

(2) adding modified nano alumina into the pretreated rapeseed insulating oil obtained in the step (1), wherein the addition amount of the modified nano alumina is 1-5% of the weight of the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation to obtain antioxidant rapeseed insulating oil;

the modified nano-alumina is prepared by the following steps:

s1, adding a crystal form control agent which is 0.5-2.0% of the dry weight of aluminum nitrate into an aluminum nitrate solution, and uniformly stirring and mixing to obtain a mixed solution, wherein the crystal form control agent is composed of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate;

s2, dropwise adding ammonia water into the mixed solution prepared in the step S1 under a stirring state until the pH value of the mixed solution is 8.0-9.5, stirring and reacting for 30-60 min, aging for 12-24 h, filtering to obtain a filter cake, and washing and drying the filter cake to obtain a precursor precipitate;

s3, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 8-10 ℃/min, the temperature is 1000-1200 ℃, and the time is 2-3 h;

and S4, mixing the nano-alumina powder obtained in the step S3 with deionized water to obtain a nano-alumina suspension, adding a surface modifier into the nano-alumina suspension, performing ultrasonic oscillation, and then filtering, washing and drying to obtain the modified nano-alumina.

Preferably, in the preparation method, the rapeseed insulating oleic acid value is 0.01-0.03 mgKOH/g, the closed flash point is 260-270 ℃, and the breakdown voltage is 70-80 kV.

Preferably, in the above preparation method, in the step (1), the mechanical stirring process parameters are as follows: the stirring speed is 250-300 r/min, and the stirring time is 30-60 min; in the step (2), the ultrasonic oscillation process parameters are as follows: the ultrasonic oscillation power is 1000-1200W, and the time is 30-60 min.

Preferably, in the preparation method, the mass ratio of the sodium citrate to the polyvinylpyrrolidone to the dioctyl sodium sulfosuccinate in the crystal form control agent is 2-3: 1-2: 3-5.

Preferably, in the preparation method, the concentration of the aluminum nitrate solution is 0.5-2.0 mol/L, and the volume percentage concentration of the ammonia water is 15-25%.

Preferably, in the preparation method, the solid content of the nano-suspension is 10-25%.

Preferably, in the preparation method, the surface modifier consists of polyethylene glycol, sodium laureth sulfate and a silane coupling agent, and the mass ratio of the polyethylene glycol to the sodium laureth sulfate to the silane coupling agent in the surface modifier is 1-3: 2-5: 3-7. The surface modifier is adopted to carry out surface modification on the nano aluminum oxide to form an organic-inorganic hybrid network structure, so that the bonding force of the nano aluminum oxide and the insulating oil interface is enhanced, and the dispersibility and stability of the nano aluminum oxide in the insulating oil are improved.

Preferably, in the preparation method, the addition amount of the surface modifier is 0.8-2.5% of the dry weight of the nano alumina in the nano alumina suspension.

Preferably, in the above preparation method, in step S2, the drying process includes: drying for 0.5-1 h at 60-80 ℃ by microwave.

Compared with the prior art, the invention has the following beneficial effects:

1. in the preparation method, the nanometer alumina particles are adopted to modify the rapeseed insulating oil, so that the oxidation resistance of the rapeseed insulating oil is improved. The nanometer alumina modified rapeseed insulating oil can enhance the oxidation resistance of the rapeseed insulating oil on the premise of ensuring the electrical insulating property of the rapeseed insulating oil, delay the reduction rate of the insulating property of the rapeseed insulating oil caused by oxidation, reduce the potential safety hazard and ensure that the transformer runs more safely, reliably and stably.

2. In the preparation method, the crystal form control agent consisting of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate is added in the preparation process of the nano-alumina, so that the prepared magnesium oxide has controllable particle size, uniform distribution and fine particles, the nano-alumina has higher specific surface area and surface energy, can adsorb more active oxygen in the insulating oil, and improves the oxidation resistance of the rapeseed insulating oil. And then, surface modification is carried out on the nano aluminum oxide by adopting a surface modifier, so that the dispersibility and stability of the nano aluminum oxide in the insulating oil are enhanced.

Detailed Description

The following detailed description will clearly and completely describe the technical solutions of the present invention, but does not limit the scope of the present invention.

Example 1

A preparation method of antioxidant rapeseed insulating oil comprises the following steps:

(1) drying the rapeseed insulating oil for 24 hours at 100 ℃ under a vacuum condition, then heating the rapeseed insulating oil to 60 ℃, and stirring for 60 minutes at the rotating speed of 250r/min to obtain the pretreated rapeseed insulating oil;

(2) adding 1 percent of modified nano alumina in the weight of the pretreated rapeseed insulating oil into the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation for 30min under the condition that the ultrasonic oscillation power is 1000W to obtain the antioxidant rapeseed insulating oil.

The modified nano-alumina is prepared by the following steps:

s1, adding a crystal form control agent which is 1.2% of the dry weight of aluminum nitrate into an aluminum nitrate solution with the concentration of 1.0mol/L, and uniformly stirring and mixing to obtain a mixed solution, wherein the crystal form control agent consists of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate in a mass ratio of 2:1: 3;

s2, dropwise adding ammonia water with the volume percentage concentration of 20% into the mixed solution under the stirring state until the PH of the mixed solution is 8.0-8.5, stirring and reacting for 60min, aging for 12h, filtering to obtain a filter cake, washing the filter cake with deionized water for 3 times, and performing microwave drying at 60 ℃ for 1h to obtain a precursor precipitate;

s3, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 10 ℃/min, the temperature is 1100 ℃, and the time is 3 h;

s4, mixing nano-alumina powder with deionized water to obtain a nano-alumina suspension with the solid content of 20%, adding 1.5% of a surface modifier of the nano-alumina powder into the nano-alumina suspension, then carrying out ultrasonic oscillation for 40min under the condition that the ultrasonic oscillation power is 1000W, then filtering to obtain a precipitate, washing with the deionized water for 3 times, and carrying out vacuum drying at 100 ℃ for 2h to obtain the modified nano-alumina. The surface modifier consists of polyethylene glycol, sodium laureth sulfate and a silane coupling agent in a mass ratio of 1:3: 5.

Example 2

The present embodiment is different from embodiment 1 in that: the addition amount of the modified nano alumina in the step (2) is 2% of the weight of the pretreated rapeseed insulating oil, and other steps and process parameters are the same as those in the example 1.

Example 3

The present embodiment is different from embodiment 1 in that: the addition amount of the modified nano alumina in the step (2) is 3% of the weight of the pretreated rapeseed insulating oil, and other steps and process parameters are the same as those in the example 1.

Example 4

The present embodiment is different from embodiment 1 in that: the addition amount of the modified nano alumina in the step (2) is 4% of the weight of the pretreated rapeseed insulating oil, and other steps and process parameters are the same as those in the example 1.

Example 5

A preparation method of antioxidant rapeseed insulating oil comprises the following steps:

(1) drying the rapeseed insulating oil for 24 hours at 100 ℃ under a vacuum condition, then heating the rapeseed insulating oil to 60 ℃, and stirring for 30 minutes at the rotating speed of 300r/min to obtain the pretreated rapeseed insulating oil;

(2) adding modified nano-alumina accounting for 1.5 percent of the weight of the pretreated rapeseed insulating oil into the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation for 30min under the condition that the ultrasonic oscillation power is 1000W to obtain the antioxidant rapeseed insulating oil.

The modified nano-alumina is prepared by the following steps:

s1, adding a crystal form control agent which is 1.8% of the dry weight of aluminum nitrate into an aluminum nitrate solution with the concentration of 1.2mol/L, and uniformly stirring and mixing to obtain a mixed solution, wherein the crystal form control agent is composed of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate with the mass ratio of 3:1.5: 4;

s2, dropwise adding ammonia water with the volume percentage concentration of 20% into the mixed solution under the stirring state until the PH of the mixed solution is 8.5-9.0, stirring and reacting for 60min, aging for 24h, filtering to obtain a filter cake, washing the filter cake with deionized water for 3 times, and performing microwave drying at 60 ℃ for 1h to obtain a precursor precipitate;

s3, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 10 ℃/min, the temperature is 1150 ℃, and the time is 2.5 h;

s4, mixing nano-alumina powder with deionized water to obtain a nano-alumina suspension with the solid content of 15%, adding 2% of a surface modifier of the nano-alumina powder into the nano-alumina suspension, then carrying out ultrasonic oscillation for 40min under the condition that the ultrasonic oscillation power is 1000W, then filtering to obtain a precipitate, washing with the deionized water for 3 times, and carrying out vacuum drying at 100 ℃ for 2h to obtain the modified nano-alumina. The surface modifier consists of polyethylene glycol, sodium laureth sulfate and a silane coupling agent in a mass ratio of 2.5:4: 7.

Comparative example 1

A preparation method of antioxidant rapeseed insulating oil comprises the following steps:

(1) drying the rapeseed insulating oil for 24 hours at 100 ℃ under a vacuum condition, then heating the rapeseed insulating oil to 60 ℃, and stirring for 60 minutes at the rotating speed of 250r/min to obtain the pretreated rapeseed insulating oil;

(2) adding 1% of nano alumina in the weight of the pretreated rapeseed insulating oil into the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation for 30min under the condition that the ultrasonic oscillation power is 1000W to obtain the antioxidant rapeseed insulating oil.

Wherein, the nanometer alumina is prepared by the following steps:

s1, dropwise adding ammonia water with the volume percentage concentration of 20% into an aluminum nitrate solution with the concentration of 1.0mol/L under the stirring state until the PH of the mixed solution is 8.0-8.5, stirring and reacting for 60min, aging for 12h, filtering to obtain a filter cake, washing the filter cake with deionized water for 3 times, and performing microwave drying at 60 ℃ for 1h to obtain a precursor precipitate;

s2, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 10 ℃/min, the temperature is 1100 ℃, and the time is 3 h.

Comparative example 2

A preparation method of antioxidant rapeseed insulating oil comprises the following steps:

(1) drying the rapeseed insulating oil for 24 hours at 100 ℃ under a vacuum condition, then heating the rapeseed insulating oil to 60 ℃, and stirring for 60 minutes at the rotating speed of 250r/min to obtain the pretreated rapeseed insulating oil;

(2) adding 1% of nano alumina in the weight of the pretreated rapeseed insulating oil into the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation for 30min under the condition that the ultrasonic oscillation power is 1000W to obtain the antioxidant rapeseed insulating oil.

Wherein, the nanometer alumina is prepared by the following steps:

s1, adding a crystal form control agent which is 1.2% of the dry weight of aluminum nitrate into an aluminum nitrate solution with the concentration of 1.0mol/L, and uniformly stirring and mixing to obtain a mixed solution, wherein the crystal form control agent consists of sodium citrate, polyvinylpyrrolidone and dioctyl sodium sulfosuccinate in a mass ratio of 2:1: 3;

s2, dropwise adding ammonia water with the volume percentage concentration of 20% into the mixed solution under the stirring state until the PH of the mixed solution is 8.0-8.5, stirring and reacting for 60min, aging for 12h, filtering to obtain a filter cake, washing the filter cake with deionized water for 3 times, and performing microwave drying at 60 ℃ for 1h to obtain a precursor precipitate;

s3, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 10 ℃/min, the temperature is 1100 ℃, and the time is 3 h.

Comparative example 3

A preparation method of antioxidant rapeseed insulating oil comprises the following steps:

(1) drying the rapeseed insulating oil for 24 hours at 100 ℃ under a vacuum condition, then heating the rapeseed insulating oil to 60 ℃, and stirring for 60 minutes at the rotating speed of 250r/min to obtain the pretreated rapeseed insulating oil;

(2) adding 1% of nano alumina in the weight of the pretreated rapeseed insulating oil into the pretreated rapeseed insulating oil, and then performing ultrasonic oscillation for 30min under the condition that the ultrasonic oscillation power is 1000W to obtain the antioxidant rapeseed insulating oil.

Wherein, the nanometer alumina is prepared by the following steps:

s1, dropwise adding ammonia water with the volume percentage concentration of 20% into an aluminum nitrate solution with the concentration of 1.0mol/L under the stirring state until the PH of the mixed solution is 8.0-8.5, stirring and reacting for 60min, aging for 12h, filtering to obtain a filter cake, washing the filter cake with deionized water for 3 times, and performing microwave drying at 60 ℃ for 1h to obtain a precursor precipitate;

s2, calcining the precursor precipitate, and then grinding to obtain the nano-alumina powder, wherein the calcining process parameters are as follows: the heating rate is 10 ℃/min, the temperature is 1100 ℃, and the time is 3 h;

s3, mixing nano-alumina powder with deionized water to obtain a nano-alumina suspension with the solid content of 20%, adding 1.5% of a surface modifier of the nano-alumina powder into the nano-alumina suspension, then carrying out ultrasonic oscillation for 40min under the condition that the ultrasonic oscillation power is 1000W, then filtering to obtain a precipitate, washing with the deionized water for 3 times, and carrying out vacuum drying at 100 ℃ for 2h to obtain the modified nano-alumina. The surface modifier consists of polyethylene glycol, sodium laureth sulfate and a silane coupling agent in a mass ratio of 1:3: 5.

The nano-alumina prepared in example 1, example 5 and comparative examples 1 to 3 was measured for particle size by laser particle size analysis (D50 and D90), and the results are shown in table 1.

Table 1: particle size distribution of nano alumina prepared in examples and comparative examples

	D50(nm)	D90(nm)
			Example 1	25	37
Example 5	28	40
			Comparative example 1	153	284
Comparative example 2	31	56
			Comparative example 3	137	229

As can be seen from Table 1, the nano-alumina prepared by the present invention has fine particles, uniform particle size and narrow particle size distribution.

The rapeseed insulating oil prepared in the examples 1 to 5 and the comparative examples 1 to 3 is subjected to a thermal aging test, and the test steps are as follows: and (3) placing the insulating oil sample in an aging tank, pumping out residual air in the tank, filling nitrogen, sealing, and placing the aging tank filled with the oil product in an aging box at 130 ℃ for thermal aging. The peroxide value of the rapeseed insulating oil is detected by referring to GB/T5538-.

Table 2 shows the results of the measurements of peroxide value, acid value, moisture content and volume resistivity of the rapeseed insulating oil before and after the thermal aging.

Table 2: performance index of rapeseed insulating oil prepared in examples and comparative examples

It can be seen from the table that the oxidation resistant rapeseed insulating oil prepared by the method provided by the present invention has a peroxide value superior to that of the unmodified rapeseed insulating oil, indicating that the oxidation resistant rapeseed insulating oil of the present invention has good oxidation resistance. In addition, the indexes such as acid value, water content, volume resistivity and the like of the antioxidant rapeseed insulating oil obtained by the method provided by the invention are superior to those of the unmodified rapeseed insulating oil, which shows that the insulating property of the antioxidant rapeseed insulating oil prepared by the method is maintained and superior to that of the unmodified rapeseed insulating oil.

The foregoing is a more detailed description of the invention in connection with specific/preferred embodiments and is not intended to limit the practice of the invention to those descriptions. It will be apparent to those skilled in the art that various substitutions and modifications can be made to the described embodiments without departing from the spirit of the invention, and such substitutions and modifications are to be considered as within the scope of the invention.