CN115746946A - Preparation method of cracked transformer reclaimed oil based on graphene column chromatography - Google Patents

Abstract

The invention discloses a preparation method of pyrolysis transformer regenerated oil based on graphene column chromatography. Waste transformer oil is used as raw material, graphene and column chromatography silica gel powder are used as stationary phase, n-hexane is used as mobile phase, and column chromatography is used for separation Purification method to obtain regenerated transformer oil. The invention can realize high-efficiency adsorption and regeneration of waste transformer oil, improves resource utilization rate, and avoids environmental pollution and resource waste.

Description

A preparation method of pyrolysis transformer recycled oil based on graphene column chromatography

technical field

The invention relates to the technical field of transformers, in particular to a transformer oil recycling technology.

Background technique

As an extremely important medium in power transmission and transformation equipment in power systems, transformer oil is widely used in oil-immersed insulated high-voltage power transmission and transformation equipment such as transformers, current transformers, circuit breakers, and bushings, which can improve electrical insulation strength and arc extinguishing. , Improve the heat dissipation performance, etc., to ensure the safe and reliable operation of the equipment. However, with the operation of the equipment, due to the high temperature of the electrical appliances, the contact with the oxygen in the air, the entry of moisture and other factors or the synergistic effect of the transformer oil, the transformer oil will react biochemically after absorbing dissolved oxygen to form aldehydes, ketones, carboxylic acids, Compounds such as naphthenic acid will cause acid value increase, oil sludge precipitation, interfacial tension decrease, breakdown voltage, dielectric loss factor and volume resistivity unqualified and other inevitable gradual oxidation and deterioration of oil quality. If the replacement is not timely, it will lead to transformer Occurrence of accidents. Therefore, a large number of transformer deteriorating oils need to be replaced every year.

However, waste transformer oil is not a completely useless waste, it is a renewable and comprehensive utilization resource, its oxidation products only account for a small part, generally 1% to 25% of the total, and its main body is still base oil, so Direct disposal will cause waste.

Contents of the invention

Aiming at the defects of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing regenerated transformer oil by pyrolysis based on graphene column chromatography, so as to realize the regeneration of waste transformer oil.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A preparation method of pyrolysis transformer regenerated oil based on graphene column chromatography, using waste transformer oil as raw material, graphene and column chromatography silica gel powder as stationary phase, n-hexane as mobile phase, and adopting column chromatography separation and purification method to obtain Regenerated transformer oil.

Preferably, the preparation method uses a glass chromatography column as a preparation carrier, and wet-packs the column with n-hexane and column chromatography silica gel powder; The product was obtained, and finally the n-hexane solution was removed by distillation under reduced pressure.

Preferably, after wet column packing, the air in the silica gel column is exhausted by a booster pump, so as to reduce the micropore structure inside the column chromatography silica gel particles.

Preferably, the column chromatography silica gel powder is 300-400 mesh.

Preferably, the thickness of the graphene powder is 1 cm.

The invention uses waste transformer oil as a raw material, graphene and column chromatography silica gel powder as a stationary phase, and n-hexane as a mobile phase, and adopts a column chromatography separation and purification method to obtain regenerated transformer oil.

The physical and chemical properties of transformer oil before and after adsorption, as well as the results of NMR, IR and GC-GC analysis show that after using graphene composite adsorbent to adsorb and treat waste transformer oil, the oxidation products of regenerated transformer oil are significantly reduced or disappeared, and its functional group composition, overall The composition is basically the same as that of the new transformer oil, and its physical and chemical properties have been significantly improved. The volume resistivity, interfacial tension, dielectric loss factor, breakdown voltage, acid value and other indicators fully meet the national standards.

Therefore, the present invention can realize high-efficiency adsorption and regeneration of waste transformer oil, improve resource utilization, avoid environmental pollution and resource waste, and open up the application of graphene in the field of waste transformer oil adsorption and purification.

The specific technical solutions adopted by the present invention and the beneficial effects brought by them will be disclosed in detail in the following specific implementation manners combined with the accompanying drawings.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

Fig. 1 is a flow chart of purification and refining of waste transformer oil of the present invention;

Fig. 2 is the NMR spectrogram of three kinds of transformer oils;

Fig. 3 is the infrared spectrogram of waste transformer oil and regenerated transformer oil.

Detailed ways

The technical solutions of the embodiments of the present invention will be explained and described below in conjunction with the accompanying drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all of them. Based on the examples in the implementation manners, other examples obtained by those skilled in the art without making creative efforts all belong to the protection scope of the present invention.

Those skilled in the art can understand that, under the condition of no conflict, the features in the following embodiments and implementation manners can be combined with each other.

The invention uses graphene and silica gel with an interlaced layered structure to make a composite adsorbent, conducts application research on adsorption and regeneration of waste transformer oil, and performs corresponding characterization on the physical and chemical structure of graphene.

A preparation method for pyrolysis transformer regenerated oil based on graphene column chromatography, taking the replaced waste transformer oil as object, graphene and column chromatography silica gel powder (300-400 mesh) as stationary phase, n-hexane as mobile phase, Regenerated transformer oil (n-hexane, Rf=0.9) which can be recovered and reused was obtained by separation and purification by column chromatography.

As shown in Figure 1, the specific steps are as follows:

1. Take a dry and clean glass chromatography column;

2. Use n-hexane and column chromatography silica gel powder to wet-pack the column, and pressurize the pump to discharge the air in the silica gel column to reduce the micropore structure inside the column chromatography silica gel particles;

3. Spread a layer of graphene powder on the upper layer of the above-mentioned silica gel column, about 1cm thick;

4, n-hexane is used as mobile phase, and column chromatography separates and obtains fine product (Rf=0.9);

5. Distilling under reduced pressure to remove the n-hexane solution to prepare regenerated transformer oil.

Furthermore, nuclear magnetic and infrared characterizations were carried out on the prepared regenerated transformer oil.

Implement validation:

In order to verify the validity and practicability of the proposed method of the present invention, the following 4 types of methods are used for verification.

1. NMR comparison results

The components of transformer oil were detected by Bruker Avance 400MHz nuclear magnetic resonance spectrometer from Bruker, Switzerland. The temperature of the detection system was kept at 298K, TMS was used as the internal standard, each spectrum was scanned 32 times, the spectrum width was 11.5ppm, the sampling time was 2s, and the pulse interval d1 was 5s. Data processing was performed by Topspin 2.0 software that comes with NMR.

As shown in Figure 2 (processing with silica gel), in the column chromatography purification system using silica gel as the stationary phase, the integral of the chemical shift of 2.5ppm is 1.00, and the integral of the chemical shift of 6.9ppm is 0.45, compared with waste oil , the impurity content of these two places is obviously reduced, the impurity content of 2.5ppm is slightly higher than that of new oil, and the content of impurity of 6.9ppm is almost twice that of new oil, indicating that the use of column chromatography to treat waste oil has a better purification effect. It is worth noting that when using silica gel and graphene as the stationary phase (processing with Graphene and silica gel), the impurity content in the processed sample is the lowest and better than that of new oil, and the chemical shift is 2.5ppm. The integral is 0.98, and the chemical shift is The integral of 6.9ppm is 0.26, which is almost the same as the NMR integral result of new oil, and the signal peak intensity at 1.5ppm drops significantly, indicating that the functional group composition of regenerated oil obtained by treating waste transformer oil with graphene composite silica gel adsorbent is basically the same as that of new oil. Transformer oil is the same.

2. Analysis and comparison of transformer oil quality

The test method is determined by the latest national standards or electric power industry standards. The test physical properties include appearance (GB/T511), water-soluble acid (pH value) (GB/T 7598), acid value (GB/T 264), closed flash point ( GB/T261), moisture (GB/T7600), interfacial tension (GB/T 6541), dielectric dissipation factor (GB/T 5654), breakdown voltage (DL/T 507), volume resistivity (DL/T 421) , sludge and sediment (mass fraction) (GB/T511), corrosive sulfur (SH/T 0804).

The regenerated transformer oil obtained by using graphene and silica gel composite adsorbent with better regeneration effect was selected, and the oil quality was analyzed and compared with new and waste transformer oil. The performance test comparison is shown in Table 1. The electrical performance index of the regenerated oil after graphene regeneration treatment is basically the same as that of the new oil.

Table 1: Analysis results of main indicators of three transformer oils

3. Infrared comparison results

Transformer oil was detected by Nicholas NEXUS Fourier Transform Infrared Spectrometer (FT-IR).

Fig. 3 is the infrared spectrogram of waste transformer oil and regenerated transformer oil after composite adsorption of graphene and silica gel. It can be seen from the figure that methyl (—CH ₃ ) antisymmetric stretching vibration absorption is 2952cm ^-1 , symmetric stretching vibration absorption is 2858cm ^-1 , methylene (—CH ₂ —) antisymmetric stretching vibration absorption is 2918cm ^-1 , the symmetrical stretching vibration absorption of 1375cm ^-1 and 1458cm ^-1 correspond to the in-plane bending vibration absorption of methyl (—CH ₃ ) and methylene (—CH ₂ —) respectively. These polar functional groups indicate that the transformer oil is used The oxidation products produced by gradual aging in the process: ketones, aldehydes or alcohols, are consistent with the NMR results, and will eventually be further oxidized and converted into carboxylic acids. From the infrared spectrum, it can be seen that the infrared peak intensity of methyl (—CH ₃ ) and methylene (—CH ₂ —) in regenerated transformer oil after adsorption treatment of waste transformer oil decreased, indicating that its performance has improved, which is also consistent with Corresponding to the results of NMR characterization.

4. Comparison results of GC-MS

In gas-solid chromatography, the adsorbent with large surface area and certain activity is used as the stationary phase. Due to the different adsorption capacity of the adsorbent for each component, each component runs at a different speed in the chromatographic column. Mass spectrometry is an analytical method that measures the charge-to-mass ratio (charge-to-mass ratio) of ions. In a mass analyzer, electric and magnetic fields are used to cause opposite velocity dispersions, and they are respectively focused to obtain a mass spectrum, thereby determining its mass. The gas chromatography-mass spectrometer is manufactured by Agilent 6890N/5975MSD in the United States, with a sensitivity of 1pgOFN, m/z272, and S/N: 175:1.

By carefully comparing the mass spectrum components of the three transformer oils, the two oxidation products at 9.50min and 12.76min respectively assigned to butyl hydroxytoluene and bicyclo[2.2.1]heptane-1-methanesulfonic acid were quantitatively analyzed. See Table 2.

Table 2: Analysis results of oil fractions of three transformer oils by GC-MS

Among them, butylated hydroxytoluene accounts for 10.223% in waste oil, only 4.194% in new oil, and 5.999% in transformer oil after graphene regeneration; bicyclo[2.2.1]heptane-1-methanesulfonic acid is in The waste oil accounts for 10.251%, the new oil only has 2.229%, and the transformer oil after graphene regeneration has a content of 5.369%. It can be seen that the content of alkane oxides in the regenerated oil is significantly reduced, which is close to the content of new oil, indicating that the use of graphene and silica gel composite adsorbents to refine waste transformer oil is a simple and efficient regeneration process.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and those skilled in the art should understand that the present invention includes but is not limited to the accompanying drawings and the description in the above specific embodiments content. Any modifications that do not depart from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims (5)

1. A preparation method of pyrolysis transformer regenerated oil based on graphene column chromatography, characterized in that, using waste transformer oil as raw material, graphene and column chromatography silica gel powder as stationary phase, n-hexane as mobile phase, adopting column layer The method of analysis, separation and purification is used to obtain regenerated transformer oil. 2. a kind of preparation method of cracking transformer regenerated oil based on graphene column chromatography according to claim 1, is characterized in that: this preparation method is preparation carrier with glass chromatography column, with normal hexane and column chromatography silica gel powder Wet column packing; then a layer of graphene powder is spread on the upper layer of the silica gel column, n-hexane is used as the mobile phase, and the product is separated by column chromatography, and finally the n-hexane solution is removed by vacuum distillation. 3. A kind of preparation method of pyrolysis transformer regenerated oil based on graphene column chromatography according to claim 2, is characterized in that: after wet packing, utilize pressurized pump to discharge the air in the silica gel column, to reduce column Microporous structure inside chromatography silica gel particles. 4. A method for preparing regenerated transformer oil by pyrolysis based on graphene column chromatography according to claim 2, characterized in that: the column chromatography silica gel powder is 300-400 mesh. 5. A kind of preparation method of cracking transformer regenerated oil based on graphene column chromatography according to claim 2, it is characterized in that: the thickness of described graphene powder is 1cm.

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