阅读说明：本技术 一种利用纳米纤维素改性的低电导率橄榄绝缘油及其制备方法 (Low-conductivity olive insulating oil modified by nanocellulose and preparation method thereof ) 是由 张镱议 刘捷丰 许楚琦 李嘉熙 于 2021-06-09 设计创作，主要内容包括：本发明涉及一种高电压与绝缘技术领域,具体公开了利用一种利用纳米纤维素改性的低电导率橄榄绝缘油及其制备方法,包括以下步骤：S1.制备纳米纤维素颗粒；S2.将制得所述纳米纤维素加入到橄榄绝缘油中,搅拌均匀,再超声分散,最后进行烘干处理,即得纳米橄榄绝缘油。本发明纳米纤维素改性后的橄榄绝缘油与传统橄榄绝缘油相比较,具有低电导率、耐击穿和高导热性的优点,采用本发明纳米纤维素改性的橄榄绝缘油制备方法,各原料分散均匀,制备步骤简单,成本较低,利于推广和工业化生产。(The invention relates to the technical field of high voltage and insulation, and particularly discloses low-conductivity olive insulating oil modified by nanocellulose and a preparation method thereof, wherein the low-conductivity olive insulating oil comprises the following steps: s1, preparing nano cellulose particles; s2, adding the prepared nano-cellulose into olive insulating oil, uniformly stirring, performing ultrasonic dispersion, and finally performing drying treatment to obtain the nano-olive insulating oil. Compared with the traditional olive insulating oil, the olive insulating oil modified by the nano-cellulose has the advantages of low electrical conductivity, breakdown resistance and high thermal conductivity.)

1. A preparation method of low-conductivity olive insulating oil modified by nanocellulose is characterized by comprising the following steps:

s1, preparing nano cellulose particles;

s2, adding the prepared nano cellulose particles into olive insulating oil, uniformly stirring, performing ultrasonic dispersion, and finally performing drying treatment to obtain low-conductivity olive insulating oil;

the diameter of the nanocellulose particles in step S1 is 10nm to 100 nm.

2. The method for preparing the nanocellulose-modified low-conductivity olive insulating oil according to claim 1, wherein said step S1 includes the steps of:

s1.1, dispersing 9.5-10.5 parts by mass of cotton fibers in 200-210 parts by mass of a 60% sulfuric acid aqueous solution;

s1.2, performing single-mode microwave radiation hydrolysis on the mixed solution to obtain a hydrolysate;

s1.3, diluting the obtained hydrolysate, and performing centrifugal separation on the diluted hydrolysate for three times to obtain a precipitate;

s1.4, taking the precipitate for dialysis for two days, filtering the precipitate through a filter membrane after dialysis, and ultrasonically dispersing the filtrate to obtain a stable nano cellulose fiber suspension;

s1.5, drying the nano cellulose fiber suspension, sequentially washing the suspension to be neutral by using acetone and deionized water, and drying to obtain nano cellulose particles.

3. The method for preparing the nano-cellulose modified low-conductivity olive insulating oil according to claim 2, wherein in the step S1.2, the hydrolysis process parameters are as follows: the temperature is 45-47 ℃, the single-mode microwave radiation power is 100W, and the radiation time is 5-6 minutes.

4. The method for preparing the nano-cellulose modified low-conductivity olive insulating oil as claimed in claim 2, wherein in the step S1.3, the hydrolysate is diluted to 10 times of the volume of the original hydrolysate, and the diluted hydrolysate is centrifuged three times at 10000 rpm.

5. The method as claimed in claim 2, wherein the cut-off molecular weight of the dialysis membrane used in the dialysis is 8000 or more, the pore size of the filter membrane used in the dialysis is 0.45 μm, the ultrasonic power is 200W, and the ultrasonic dispersion time is 35 min.

6. The method for preparing the nanocellulose-modified low-conductivity olive insulating oil according to claim 2, wherein said drying in step S1.5 is performed in a vacuum drying oven.

7. The method as claimed in claim 1, wherein the stirring in the step S2 is magnetic stirring at 30 ℃ and 500 r/min.

8. The method of claim 1, wherein the ultrasound treatment in the step S2 is performed in six times, each time the ultrasound treatment is performed at a power of 300W and a frequency of 100kHz for 10min, and an interval between each time of the ultrasound treatment is 6 min; the drying treatment is drying for 4 hours in a vacuum drying oven at 60 ℃.

9. The nanocellulose-modified low-conductivity olive insulating oil prepared by the method for preparing the nanocellulose-modified low-conductivity olive insulating oil according to any one of claims 1 to 8.

10. The nanocellulose-modified low-conductivity olive insulating oil according to claim 9, wherein the nanocellulose is in a mass ratio of 1% to 10%.

Technical Field

The invention relates to the technical field of high voltage and insulation, in particular to low-conductivity olive insulating oil modified by nanocellulose and a preparation method thereof.

Background

Oil-filled power transformers are critical devices in the safe operation of power grids, and the failure of the oil-filled power transformers interrupts the power supply. 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. Olive oil is used as transformer insulating oil because of its advantages of being renewable, degradable, resistant to breakdown, etc. However, olive insulating oil is easily aged during long-term operation, resulting in increased electrical conductivity, decreased insulating properties, and easily causing insulation failure of a transformer. Therefore, the development of the low-conductivity olive insulating oil has high practical value.

In recent years, with the development of nanotechnology, the addition of nanoparticles is an important method for improving the performance of plant insulating oil. Therefore, the invention selects the nano cellulose particles to be added into the olive insulating oil so as to prepare the low-conductivity olive insulating oil.

Disclosure of Invention

Aiming at the problem of high electrical conductivity of the olive insulating oil, the invention aims to provide the olive insulating oil with low electrical conductivity, which can meet the requirements of thermal conductivity and insulating property of the insulating oil in a transformer and has low electrical conductivity.

The invention also aims to provide a preparation method of the low-conductivity olive insulating oil modified by the nanocellulose, which has the advantages of simple preparation steps, low cost and contribution to popularization and industrial production.

In order to achieve the above object, the present invention provides a method for preparing nanocellulose-modified low-conductivity olive insulating oil, comprising the steps of:

s1, preparing nano cellulose particles;

s2, adding the prepared nano-cellulose into olive insulating oil, uniformly stirring, performing ultrasonic dispersion, and finally performing drying treatment to obtain the nano-olive insulating oil;

the diameter of the nanocellulose particles in step S1 is 10nm to 100 nm.

Further, in the above technical solution, the step S1 includes the following steps:

s1.1, dispersing 9.5-10.5 parts by weight of cotton fibers in 200-210 parts by weight of a 60% sulfuric acid aqueous solution;

s1.2, performing single-mode microwave radiation hydrolysis on the mixed solution to obtain a hydrolysate;

s1.3, diluting the obtained hydrolysate, and performing centrifugal separation on the diluted hydrolysate for three times to obtain a precipitate;

s1.4, taking the precipitate for dialysis for two days, filtering the precipitate through a filter membrane after dialysis, and ultrasonically dispersing the filtrate to obtain a stable nano cellulose fiber suspension;

s1.5, drying the nano cellulose fiber suspension, sequentially washing the nano cellulose fiber suspension to be neutral by using acetone and deionized water, and drying to obtain nano cellulose particles.

Preferably, in the above technical scheme, in the step S1.2, the temperature of the hydrolysis process is 45-47 ℃, the radiation power of the single-mode microwave is 100W, and the radiation time is 5-6 minutes.

Preferably, in the above technical scheme, the hydrolysate in step S1.3 is diluted to 10 times of the volume of the original hydrolysate, and the diluted hydrolysate is subjected to centrifugal separation three times at a rotation speed of 10000 rpm.

Preferably, in the above technical solution, the cut-off molecular weight of the dialysis membrane used in step S1.4 is 8000 or more, the pore size of the filter membrane used is 0.45 μm, the ultrasonic power is 200W, and the ultrasonic dispersion time is 35 minutes.

Preferably, in the above technical solution, the drying in step S1.5 is performed in a vacuum drying oven.

Preferably, in the above technical solution, the stirring in step S2 is magnetic stirring at 30 ℃ and 500 r/min.

Preferably, in the above technical solution, the ultrasound in step S2 is performed for six times, each time ultrasound is performed for 10min under the conditions of 300W power and 100kHz frequency, and the interval between each two times of ultrasound is 6 min; the drying treatment is drying for 4 hours in a vacuum drying oven at 60 ℃.

The invention provides the nanocellulose-modified low-conductivity olive insulating oil prepared by the preparation method of the nanocellulose-modified low-conductivity olive insulating oil in the technical method.

Preferably, in the technical scheme, the mass ratio of the nano-cellulose in the nano-cellulose modified low-conductivity olive insulating oil is 1% -10%.

The invention has the beneficial effects that:

the preparation method provided by the invention adopts the olive insulating oil and the nano cellulose particles as raw materials, has simple preparation steps and lower cost, and is beneficial to popularization and industrial production; the nanocellulose added into the prepared product can be polarized under the action of an electric field, and a large number of traps are formed around the nanocellulose, so that migration of charged particles in oil is hindered, the conductive current is reduced, and the breakdown voltage is improved. Compared with the traditional olive insulating oil, the modified olive insulating oil has the advantages of low electrical conductivity, breakdown resistance and high thermal conductivity.

Drawings

FIG. 1 is a schematic of a flow chart for preparing a nanocellulose-modified low-conductivity olive insulating oil in accordance with an embodiment of the present invention;

FIG. 2 is a schematic diagram showing the effect of different ratios of nanocellulose particles on olive oil conductivity in an example of the present invention;

FIG. 3 is a schematic diagram illustrating the effect of different ratios of nano-cellulose nanoparticles on the thermal conductivity of olive oil in an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating the effect of different ratios of nanocellulose particles on olive oil breakdown voltage in an embodiment of the present invention.

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.

Example 1: preparation of nano-cellulose modified low-conductivity olive insulating oil

The preparation process of the nano-cellulose modified low-conductivity olive insulating oil is shown in figure 1 and specifically comprises the following steps:

s1, preparing nano cellulose particles:

s1.1, dispersing 10g of cotton fibers in 200g of a 60 mass percent sulfuric acid aqueous solution;

s1.2, performing single-mode microwave radiation hydrolysis on the mixed solution to obtain a hydrolysate; wherein the temperature in the hydrolysis process is 45 ℃, the radiation power of the single-mode microwave is 100W, and the radiation time is 5 minutes.

S1.3, diluting the obtained hydrolysate to be 10 times of the volume of the original hydrolysate, carrying out centrifugal separation on the diluted hydrolysate for three times under the condition of 10000rpm, and taking out a precipitate;

s1.4, taking the precipitate for dialysis for two days, filtering the precipitate through a filter membrane after dialysis, and ultrasonically dispersing the filtrate to obtain a stable nano cellulose fiber suspension; wherein the cut-off molecular weight of the dialysis membrane is more than 8000, the aperture of the filter membrane is 0.45 micron, the ultrasonic power is 200W, and the ultrasonic dispersion time is 35 minutes.

S1.5, drying the nano cellulose fiber suspension, sequentially washing the nano cellulose fiber suspension to be neutral by using acetone and deionized water, drying to obtain nano cellulose particles, and drying twice in a vacuum drying box. The diameter of the obtained nano-particles is 10nm-100 nm.

S2. formation of nano-cellulose modified low-conductivity olive insulating oil

Adding the prepared nano-cellulose into olive insulating oil, uniformly stirring, performing magnetic stirring at the temperature of 30 ℃ at the speed of 500r/min, performing ultrasonic dispersion under the ultrasonic dispersion condition of ultrasonic treatment for 10min six times at the ultrasonic power of 300W and the ultrasonic frequency of 100kHz at intervals of 6min, and finally performing drying treatment, wherein the drying condition is drying for 4h in a vacuum drying oven at the temperature of 60 ℃. Obtaining the nano-cellulose modified olive insulating oil, wherein the mass fraction of the nano-particles is 1%.

Example 2

S1, preparing nano cellulose particles:

s1.1, dispersing 9.5g of cotton fibers in 200g of sulfuric acid aqueous solution with the mass percentage concentration of 60%;

s1.2, performing single-mode microwave radiation hydrolysis on the mixed solution to obtain a hydrolysate; wherein the temperature in the hydrolysis process is 45 ℃, the radiation power of the single-mode microwave is 100W, and the radiation time is 6 minutes.

S1.3, diluting the obtained hydrolysate to be 10 times of the volume of the original hydrolysate, carrying out centrifugal separation on the diluted hydrolysate for three times under the condition of 10000rpm, and taking out a precipitate;

s1.4, taking the precipitate for dialysis for two days, filtering the precipitate through a filter membrane after dialysis, and ultrasonically dispersing the filtrate to obtain a stable nano cellulose fiber suspension; wherein the cut-off molecular weight of the dialysis membrane is more than 8000, the aperture of the filter membrane is 0.45 micron, the ultrasonic power is 200W, and the ultrasonic dispersion time is 35 minutes.

S1.5, drying the nano cellulose fiber suspension, sequentially washing the nano cellulose fiber suspension to be neutral by using acetone and deionized water, drying to obtain nano cellulose particles, and drying twice in a vacuum drying box. The diameter of the obtained nano-particles is 10nm-100 nm.

S2. formation of nano-cellulose modified low-conductivity olive insulating oil

Adding the prepared nano-cellulose into olive insulating oil, uniformly stirring, performing magnetic stirring at the temperature of 30 ℃ at a speed of 500r/min, performing ultrasonic dispersion under the ultrasonic dispersion condition of ultrasonic treatment for 10min six times at an interval of 6min each time under the ultrasonic power of 300W and the ultrasonic frequency of 100kHz, and finally performing drying treatment, wherein the drying condition is drying for 4h in a vacuum drying oven at the temperature of 60 ℃. Obtaining the nano-cellulose modified olive insulating oil, wherein the mass fraction of the nano-particles is 2%.

Example 3

S1, preparing nano cellulose particles:

s1.1, dispersing 10.5g of cotton fibers in 210g of sulfuric acid aqueous solution with the mass percentage concentration of 60%;

s1.2, performing single-mode microwave radiation hydrolysis on the mixed solution to obtain a hydrolysate; wherein the temperature in the hydrolysis process is 47 ℃, the single-mode microwave radiation power is 100W, and the radiation time is 5 minutes.

S1.3, diluting the obtained hydrolysate to be 10 times of the volume of the original hydrolysate, carrying out centrifugal separation on the diluted hydrolysate for three times under the condition of 10000rpm, and taking out a precipitate;

s1.4, taking the precipitate for dialysis for two days, filtering the precipitate through a filter membrane after dialysis, and ultrasonically dispersing the filtrate to obtain a stable nano cellulose fiber suspension; wherein the cut-off molecular weight of the dialysis membrane is more than 8000, the aperture of the filter membrane is 0.45 micron, the ultrasonic power is 200W, and the ultrasonic dispersion time is 35 minutes.

S1.5, drying the nano cellulose fiber suspension, sequentially washing the nano cellulose fiber suspension to be neutral by using acetone and deionized water, drying to obtain nano cellulose particles, and drying twice in a vacuum drying box. The diameter of the obtained nano-particles is 10nm-100 nm.

S2. formation of nano-cellulose modified low-conductivity olive insulating oil

Adding the prepared nano-cellulose into olive insulating oil, uniformly stirring, performing magnetic stirring at the temperature of 30 ℃ at a speed of 500r/min, performing ultrasonic dispersion under the ultrasonic dispersion condition of ultrasonic treatment for 10min six times at an interval of 6min each time under the ultrasonic power of 300W and the ultrasonic frequency of 100kHz, and finally performing drying treatment, wherein the drying condition is drying for 4h in a vacuum drying oven at the temperature of 60 ℃. Obtaining the nano-cellulose modified olive insulating oil, wherein the mass fraction of the nano-particles is 4%.

Example 4

S1, preparing nano cellulose particles:

s1.1, dispersing 10g of cotton fibers in 200g of a 60 mass percent sulfuric acid aqueous solution;

s1.2, performing single-mode microwave radiation hydrolysis on the mixed solution to obtain a hydrolysate; wherein the temperature in the hydrolysis process is 45 ℃, the radiation power of the single-mode microwave is 100W, and the radiation time is 6 minutes.

S1.3, diluting the obtained hydrolysate to be 10 times of the volume of the original hydrolysate, carrying out centrifugal separation on the diluted hydrolysate for three times under the condition of 10000rpm, and taking out a precipitate;

s1.4, taking the precipitate for dialysis for two days, filtering the precipitate through a filter membrane after dialysis, and ultrasonically dispersing the filtrate to obtain a stable nano cellulose fiber suspension; wherein the cut-off molecular weight of the dialysis membrane is more than 8000, the aperture of the filter membrane is 0.45 micron, the ultrasonic power is 200W, and the ultrasonic dispersion time is 35 minutes.

S1.5, drying the nano cellulose fiber suspension, sequentially washing the nano cellulose fiber suspension to be neutral by using acetone and deionized water, drying to obtain nano cellulose particles, and drying twice in a vacuum drying box. The diameter of the obtained nano-particles is 10nm-100 nm.

S2. formation of nano-cellulose modified low-conductivity olive insulating oil

Adding the prepared nano-cellulose into olive insulating oil, uniformly stirring, performing magnetic stirring at the temperature of 30 ℃ at a speed of 500r/min, performing ultrasonic dispersion under the ultrasonic dispersion condition of ultrasonic treatment for 10min six times at an interval of 6min each time under the ultrasonic power of 300W and the ultrasonic frequency of 100kHz, and finally performing drying treatment, wherein the drying condition is drying for 4h in a vacuum drying oven at the temperature of 60 ℃. Obtaining the nano-cellulose modified olive insulating oil, wherein the mass fraction of the nano-particles is 10%.

The results of the tests on the electrical conductivity, the thermal conductivity and the breakdown voltage of the low-conductivity insulating oil and the unmodified insulating oil prepared in the above examples 1 to 4 are shown in fig. 2 to 4, it can be seen from fig. 2 that the electrical conductivity of the olive insulating oil is reduced firstly and then increased along with the increase of the addition amount of the nano cellulose particles, and the electrical conductivity of the olive insulating oil is far lower than that of the olive insulating oil without the addition of the nano cellulose particles under the condition that the addition amount of the nano cellulose particles is 1 to 10 percent; particularly, when the addition amount of the nanocellulose particles is about 4%, the reduction of the electrical conductivity of the olive insulating oil without the nanocellulose particles is more prominent; from fig. 3, it can be known that the thermal conductivity of the olive insulating oil tends to increase first and then decrease as the addition amount of the nano cellulose particles increases, and the thermal conductivity of the olive insulating oil is higher than that of the olive insulating oil without the addition of the nano cellulose particles under the condition that the addition amount of the nano cellulose particles is 1% -10%; particularly, when the addition amount of the nano cellulose particles is about 4 percent, the thermal conductivity coefficient is obviously increased compared with that of olive insulating oil without the nano cellulose particles; from fig. 4, it can be known that the breakdown voltage is higher than the breakdown voltage of the olive insulating oil without the addition of the nano cellulose particles under the condition that the addition amount of the nano cellulose particles is 1% -10%; particularly, when the addition amount of the nano-cellulose particles is about 2%, the breakdown voltage of the olive insulating oil is far higher than that of the olive insulating oil without the nano-cellulose particles.

In conclusion, the nano-cellulose modified olive insulating oil has low electrical conductivity, high breakdown voltage and high thermal conductivity coefficient, and the method for preparing the nano-cellulose modified low-conductivity olive insulating oil has simple steps and low cost, and is beneficial to popularization and industrial production.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be limited only by the claims and the equivalents thereof.