A transformer oil additive, a preparation method and application thereof in transformer oil gas adsorption

Abstract

The application provides a transformer oil additive, a preparation method and application thereof in transformer oil gas adsorption, and belongs to the technical field of transformer oil dissolved gas adsorption.The transformer oil additive is activated carbon loaded with monatomic nanometer palladium, and is prepared by mixing and stirring Na2PdCl4 aqueous solution, PVA solution and NaBH4 solution to obtain a palladium sol, acidifying the palladium sol with concentrated sulfuric acid, then adding activated carbon and stirring, filtering, washing, drying and calcining to obtain the transformer oil additive, wherein the loading amount of monatomic nanometer palladium on the activated carbon is 1-2 wt%.The transformer oil additive is doped in transformer oil to prepare an insulating fluid, so that the adsorption of H2 in the transformer oil can be improved, and partial discharge faults can be eliminated, which has important significance for relieving transformer faults and guaranteeing safe and stable operation of the transformer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of transformer oil dissolved gas adsorption, and particularly relates to a transformer oil additive, a preparation method and application thereof in transformer oil gas adsorption. BACKGROUND

[0002] The main reason for hydrogen generation in transformer failure is thermal decomposition of insulating materials. During the operation of the transformer, the insulating materials are in a high-temperature and high-pressure environment, and are exposed to oil for a long time. When the transformer fails due to aging, arc breakdown or short circuit, high temperature and high energy conditions are generated, and under such high-temperature environmental conditions, the insulating materials may undergo thermal decomposition, thereby generating a large amount of dangerous gas. Among these dangerous gases, hydrogen (H2) is the most dangerous gas, which can be generated in large quantities through discharge and can also be formed in stray gas. Stray gas is the result of chemical reaction of oil phase at normal working temperature of the transformer. It is very important to detect and discharge hydrogen generated inside the transformer in time. Once hydrogen is found to be generated inside the transformer, measures should be taken immediately to ensure safety, such as discharging hydrogen, ventilation, and ensuring that hydrogen does not accumulate to a dangerous concentration that can cause explosion or fire. At the same time, regular maintenance and inspection can effectively prevent the harm caused by hydrogen generated by transformer failure. Therefore, detection, measurement and adsorption of hydrogen in transformer oil are very important. SUMMARY

[0003] To solve the above technical problems, the present application provides a transformer oil additive, a preparation method and application thereof in transformer oil gas adsorption, so as to reduce the content of H2 in transformer oil and eliminate partial discharge failure.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0005] One of the technical solutions of the present application is:

[0006] A transformer oil additive (Pd / AC) is active carbon (AC) loaded with single-atom nano-palladium (Pd), and the loading amount of the single-atom nano-palladium on the active carbon is 1-2wt%.

[0007] The purpose of setting the loading amount to 1-2wt% is that the adsorption activity is the highest in this loading amount range. If it is lower than 1wt%, it is difficult for hydrogen to contact with the reactants, thereby making it difficult to promote the reaction. If it is higher than 2wt%, the active sites are too close to each other, which easily shields each other, and even forms an overload state, resulting in reduction or even failure of reaction efficiency.

[0008] The second technical solution of the present application is:

[0009] A preparation method of the transformer oil additive comprises the following steps:

[0010] The Na2PdCl4 aqueous solution, the PVA solution and the NaBH4 solution are mixed and stirred to obtain a palladium sol, the palladium sol is acidified with concentrated sulfuric acid, then activated carbon is added and stirred, and the palladium sol is filtered, washed, dried and calcined to obtain the transformer oil additive.

[0011] Further, the concentration of the Na2PdCl4 aqueous solution is 0.3 mmol / L, the concentration of the PVA solution is 1.5-2 wt%, and the concentration of the NaBH4 solution is 0.05-0.15 mol / L.

[0012] Further, the amount ratio of the Na2PdCl4 aqueous solution, the PVA solution and the NaBH4 solution is mass ratio (220-280):(0.5-2.5):(0.5-2.5).

[0013] Preferably, the amount ratio of the Na2PdCl4 aqueous solution, the PVA solution and the NaBH4 solution is mass ratio (230-260):(1-2):(1-2).

[0014] Further, the palladium sol is acidified with concentrated sulfuric acid to pH=1-7. The acidification reaction makes the colloid coagulate to form a stable three-dimensional skeleton structure.

[0015] Further, the activated carbon needs to be pretreated before being added, and the pretreatment step is as follows: the activated carbon is soaked in a 0.5-1.5 mol / L NaOH solution at 60-100 DEG C for 10-14 h, then washed with deionized water until pH=5-9, and dried at 50-90 DEG C for 10-14 h, and then calcined at 300-700 DEG C under N2 atmosphere for 1-5 h.

[0016] Further, the drying temperature is 50-90 DEG C, and the drying time is 10-14 h. The drying function can reduce the effect of water, maintain the original properties and quality of the material, and improve the stability of the material through drying treatment.

[0017] Further, the calcination temperature is 150-250 DEG C, and the calcination time is 1-5 h. During the calcination process, impurities may react, evaporate or oxidize, etc., so as to be removed or reduce their content. Calcination can improve the purity and cleanliness of the sample, and improve the adsorption performance of the material through drying.

[0018] More specifically, the preparation method of the transformer oil additive comprises the following steps:

[0019] The 220-280 mL, 0.3 mmol / L Na2PdCl4 aqueous solution is mixed with 0.5-2.5 mL, 1.5-2 wt% PVA solution under stirring to obtain a yellow-brown solution, then 0.5-2.5 mL, 0.05-0.15 mol / L NaBH4 solution is added dropwise under magnetic stirring at a speed of 200-900 r / min to obtain a deep brown palladium sol, after stirring for 1-8 min, the palladium sol is acidified to pH=1-7 with concentrated sulfuric acid, then activated carbon is added and stirred for 0.5-3.5 h, the slurry is filtered, and the palladium content on the activated carbon carrier is checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to meet the loading amount of monatomic nano-palladium on the activated carbon of 1.5-2 wt%, and the activated carbon is washed thoroughly with deionized water until there is no Cl - exists, then dried at 50-90℃ for 10-14 h, and then calcined in flowing air at 150-250℃ for 1-5 h to remove the PVA protective agent to obtain the transformer oil additive.

[0020] The third technical scheme of the present application is:

[0021] A transformer oil-based insulating fluid is obtained by mixing the transformer oil additive with transformer oil, and then ultrasonic treatment and degassing.

[0022] Further, the degassing pressure is less than 0.1 kPa, and the time is 20-60 h. The gas in the transformer oil affects the properties of the transformer oil and the working efficiency and service life of the transformer, and the insulation performance of the material is improved by drying treatment.

[0023] Further, the ultrasonic treatment time is 1.5-3 h.

[0024] Further, the transformer oil additive and the transformer oil are magnetically stirred at 100-800 r / min for 5-30 min.

[0025] Further, the mass ratio of the transformer oil additive to the transformer oil is 1:12.

[0026] The fourth technical scheme of the present application is:

[0027] The application of the transformer oil additive or the transformer oil-based insulating fluid in transformer oil gas adsorption.

[0028] Compared with the prior art, the present application has the following advantages and technical effects:

[0029] (1) Pd on AC unique functional groups improve the efficiency of H2 adsorption, in which the hydroxyl functional group -OH can interact with hydrogen by hydrogen bond and hydrogen, increase the adsorption capacity of hydrogen on the surface of activated carbon, two oxygen atoms of ketone functional group (C=O) can form hydrogen bond with hydrogen, improve the adsorption capacity of hydrogen, plus the metal properties of Pd also have adsorption effect on H2.

[0030] (2) The present application prepares insulating fluid by doping Pd / AC additive in transformer oil, uses the high affinity of H2 to the active sites on the surface of Pd / AC, reduces the content of H2 in transformer oil through the doping of Pd / AC, so as to improve the adsorption of H2 in transformer oil and eliminate partial discharge failure, which has important significance for relieving transformer failure and ensuring the safe and stable operation of transformer. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which constitute a part of this application, are intended to provide further understanding of the application and are incorporated herein for explanation of the application and are not intended as an undue limitation on the application. In the drawings:

[0032] Figure 1 The scanning electron microscope graph of the transformer oil additive (Pd / AC) prepared for the embodiment 1 of the present application. DETAILED DESCRIPTION

[0033] The various illustrative embodiments of the present application will now be described in detail below. The detailed description is not intended to be taken in a limiting sense and is understood to be merely describing certain aspects, features and implementation of the present application.

[0034] It should be understood that the terms used herein are merely for describing particular embodiments and are not intended to limit the present application. In addition, for numerical ranges in the present application, it should be understood that every intermediate value between the upper limit and the lower limit of the range is specifically disclosed. Each intermediate value between any stated value or stated range, as well as any other stated value or intermediate value in the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be included or excluded independently.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict, the content of the present specification will control.

[0036] Many modifications and variations to the illustrative embodiments described herein will be apparent to those of ordinary skill in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the present application. Other embodiments will be apparent to those of ordinary skill in the art from consideration of the description and practice of the present application. The description and examples are exemplary only.

[0037] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed material or list of materials.

[0038] The embodiment of the present application provides a transformer oil additive (Pd / AC), which is activated carbon (AC) loaded with single-atom nano-palladium (Pd), and the loading amount of the single-atom nano-palladium on the activated carbon is 1-2 wt%.

[0039] The embodiment of the present application further provides a preparation method of the transformer oil additive, which comprises the following steps:

[0040] The aqueous Na2PdCl4 solution, the PVA solution and the NaBH4 solution are mixed and stirred to obtain a palladium sol, the palladium sol is acidified by concentrated sulfuric acid, then the activated carbon is added and stirred, and then filtration, washing, drying and calcination are performed to obtain the transformer oil additive.

[0041] In the preferred embodiment of the present application, the concentration of the aqueous Na2PdCl4 solution is 0.3 mmol / L, the concentration of the PVA solution is 1.5-2 wt%, and the concentration of the NaBH4 solution is 0.05-0.15 mol / L.

[0042] In the preferred embodiment of the present application, the mass ratio of the aqueous Na2PdCl4 solution, the PVA solution and the NaBH4 solution is (220-280):(0.5-2.5):(0.5-2.5). More preferably, the mass ratio of the aqueous Na2PdCl4 solution, the PVA solution and the NaBH4 solution is (230-260):(1-2):(1-2).

[0043] In the preferred embodiment of the present application, the palladium sol is acidified by concentrated sulfuric acid to pH=1-7.

[0044] In the preferred embodiment of the present application, the drying temperature is 50-90℃, and the time is 10-14h. More preferably, the drying temperature is 60-85℃, and the time is 11-13h.

[0045] In the preferred embodiment of the present application, the calcination temperature is 150-250℃, and the time is 1-5h. More preferably, the calcination temperature is 170-220℃, and the time is 2-4.5h.

[0046] In the embodiment of the present application, the activated carbon is pretreated before being used, and the pretreatment step is as follows: the activated carbon is soaked in 0.5-1.5 mol / L NaOH solution at 60-100 ℃ for 10-14 h, then washed with deionized water until pH=5-9, and dried at 50-90 ℃ for 10-14 h, and then calcined at 300-700 ℃ under N2 atmosphere for 1-5 h.

[0047] The embodiment of the present application also provides a transformer oil-based insulation fluid, wherein the transformer oil additive is mixed with transformer oil, and then ultrasonic treatment and degassing are performed.

[0048] In the embodiment of the present application, the degassing pressure is less than 0.1 kPa, and the time is 20-60 h.

[0049] In the embodiment of the present application, the ultrasonic treatment time is 1.5-3 h.

[0050] In the embodiment of the present application, the transformer oil additive and the transformer oil are magnetically stirred at 100-800 r / min for 5-30 min.

[0051] In the embodiment of the present application, the mass ratio of the transformer oil additive to the transformer oil is 1:12.

[0052] The transformer oil additive or the transformer oil-based insulation fluid prepared in the embodiment of the present application can be further applied to adsorption of gas in transformer oil.

[0053] The technical solutions of the present application are further described below through examples.

[0054] Example 1

[0055] AC pretreatment: the activated carbon is soaked in 1 mol / L NaOH solution at 80 ℃ for 12 h, and the mass ratio of the activated carbon to the NaOH solution is 1:2, then washed with deionized water until pH=7, and dried at 70 ℃ for 12 h, and then calcined at 500 ℃ under N2 atmosphere for 3 h to obtain the pretreated activated carbon.

[0056] Preparation of Pd / AC: 230 mL of 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 1.2 mL of 1 wt% PVA solution under stirring to obtain a yellow-brown solution, then 1 mL of 0.08 mol / L NaBH4 solution was added dropwise under magnetic stirring at a rotation speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 2 min, the palladium sol was acidified to pH = 1 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 1 h, the slurry was filtered, and the palladium content on the activated carbon carrier was detected by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading amount of monatomic nano-palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl - , then dried at 60°C for 11 h, and then calcined in flowing air at 170°C for 2 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC), the scanning electron microscope image is shown in Figure 1 , and Figure 1 It can be seen that the monatomic nano-palladium is loaded on the activated carbon.

[0057] Preparation of transformer oil-based insulating fluid: the above-mentioned transformer oil additive was mixed with transformer oil at a mass ratio of 1:12 under magnetic stirring at 200 r / min for 5 min, then ultrasonic for 1.5 h, and degassed under a pressure of less than 0.1 kPa for 20 h.

[0058] H2 gas content test

[0059] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulating fluid prepared in this embodiment using a standard gas automatic meter, then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulating fluid, which reached 52.2%.

[0060] Example 2

[0061] Preparation of Pd / AC: 230 mL of 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 1.2 mL of 1 wt% PVA solution under stirring to obtain a yellow-brown solution, then 1 mL of 0.08 mol / L NaBH4 solution was added dropwise under magnetic stirring at a rotation speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 2 min, the palladium sol was acidified to pH = 1 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 1 h, the slurry was filtered, and the palladium content on the activated carbon carrier was detected by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading amount of monatomic nano-palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl

[0062] Preparation of Pd / AC: 240 mL of 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 1.3 mL of 1 wt% PVA solution under stirring to obtain a yellow-brown solution, then 1.1 mL of 0.09 mol / L NaBH4 solution was added dropwise under magnetic stirring at a rotation speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 3 min, the palladium sol was acidified to pH = 2 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 1.5 h, the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl - was dried at 65 °C for 11.5 h, and then calcined in flowing air at 180 °C for 2.5 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0063] Preparation of transformer oil-based insulation fluid: the above-mentioned transformer oil additive was mixed with transformer oil at a mass ratio of 1:12 under magnetic stirring at 300 r / min for 8 min, and then ultrasonic for 1.8 h, and degassed under a pressure less than 0.1 kPa for 30 h.

[0064] H2 gas content test

[0065] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulation fluid, which reached 56.4%.

[0066] Example 3

[0067] Preparation of AC: 100 g of activated carbon was soaked in 1 mol / L NaOH solution at 80 °C for 12 h, and then washed with deionized water until pH = 7, and dried at 70 °C for 12 h, and then calcined at 500 °C under N2 atmosphere for 3 h to obtain the activated carbon.

[0068] Preparation of Pd / AC: 240 mL, 0.3 mmol / L of Na2PdCl4 aqueous solution was mixed with 1.4 mL, 1 wt% of PVA solution under stirring to obtain a yellow-brown solution, then 2 mL, 0.1 mol / L of NaBH4 solution was added dropwise under magnetic stirring at a speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 3 min, the palladium sol was acidified to pH = 3 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 2 h, the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic nano-palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl - was present, then dried at 70°C for 12 h, and then calcined in flowing air at 190°C for 3 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0069] Preparation of transformer oil-based insulation fluid: the above-mentioned transformer oil additive was mixed with transformer oil at a mass ratio of 1:12, and stirred at 400 r / min for 11 min, then ultrasonically treated for 3.1 h, and degassed under a pressure of less than 0.1 kPa for 40 h.

[0070] H2 gas content test

[0071] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulation fluid prepared in this embodiment using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulation fluid, which reached 57.9%.

[0072] Example 4

[0073] Pretreatment of AC: the activated carbon was soaked in 1 mol / L NaOH solution at 80°C for 12 h, and the amount ratio of activated carbon to NaOH solution was mass ratio 1:2, then washed with deionized water until pH = 7, and dried at 70°C for 12 h, then calcined at 500°C under N2 atmosphere for 3 h to obtain pretreated activated carbon.

[0074] Preparation of Pd / AC: 247 mL of 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 1.5 mL of 1 wt% PVA solution under stirring to obtain a yellow-brown solution, then 1.3 mL of 0.11 mol / L NaBH4 solution was added dropwise under magnetic stirring at a rotation speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 4 min, the palladium sol was acidified to pH = 4 with concentrated sulfuric acid, then the above pretreated activated carbon was added and stirred for 2.5 h, the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl - was present, then dried at 75 °C for 12 h, and then calcined in a flowing air at 200 °C for 3.5 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0075] Preparation of transformer oil-based insulation fluid: the above transformer oil additive was mixed with transformer oil at a mass ratio of 1:12, and stirred at 500 r / min for 14 min, then ultrasonically treated for 2.4 h, and degassed under a pressure less than 0.1 kPa for 50 h.

[0076] H2 gas content test

[0077] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulation fluid, which reached 51.4%.

[0078] Example 5

[0079] Pretreatment of AC: the activated carbon was soaked in 1 mol / L NaOH solution at 80 °C for 12 h, and the amount ratio of activated carbon to NaOH solution was mass ratio 1:2, then washed with deionized water to pH = 7, and dried at 70 °C for 12 h, then calcined at 500 °C under N2 atmosphere for 3 h to obtain pretreated activated carbon.

[0080] Preparation of Pd / AC: 235 mL of 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 1.6 mL of 1 wt% PVA solution under stirring to obtain a yellow-brown solution, then 1.4 mL of 0.12 mol / L NaBH4 solution was added dropwise under magnetic stirring at a speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 5 min, the palladium sol was acidified to pH = 5 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 3 h, the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl - was present, then dried at 80 °C for 12.5 h, and then calcined at 200 °C in a flowing air for 4 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0081] Preparation of transformer oil-based insulation fluid: the above-mentioned transformer oil additive was mixed with transformer oil at a mass ratio of 1:12, and stirred at 550 r / min for 17 min, then ultrasonically treated for 2.7 h, and degassed at a pressure of less than 0.1 kPa for 55 h.

[0082] H2 gas content test

[0083] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulation fluid, which reached 61.9%.

[0084] Example 6

[0085] Pretreatment of AC: the activated carbon was soaked in 1 mol / L NaOH solution at 80 °C for 12 h, and the amount ratio of activated carbon to NaOH solution was mass ratio 1:2, then washed with deionized water until pH = 7, and dried at 70 °C for 12 h, then calcined at 500 °C under N2 atmosphere for 3 h to obtain pretreated activated carbon.

[0086] Preparation of Pd / AC: 255 mL, 0.3 mmol / L of Na2PdCl4 aqueous solution was mixed with 1.7 mL, 1 wt% of PVA solution under stirring to obtain a yellow-brown solution, then 1.5 mL, 0.13 mol / L of NaBH4 solution was added dropwise under magnetic stirring at a speed of 600 r / min to obtain a deep brown palladium sol, after stirring for 6 min, the palladium sol was acidified to pH = 6 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 3.5 h, the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic nano-palladium on the activated carbon 1 wt%, and then washed thoroughly with deionized water until there was no Cl - was present, then dried at 85°C for 13 h, and then calcined in flowing air at 220°C for 4 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0087] Preparation of transformer oil-based insulating fluid: the above-mentioned transformer oil additive was mixed with transformer oil at a mass ratio of 1:12 under magnetic stirring at 600 r / min for 20 min, and then degassed under a pressure of less than 0.1 kPa for 55 h after ultrasonic treatment for 3 h.

[0088] H2 gas content test

[0089] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulating fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulating fluid, which reached 67.3%.

[0090] Example 7

[0091] The same as Example 1, except that the palladium sol was acidified to pH = 6 with concentrated sulfuric acid.

[0092] H2 (flow rate 150 mL / min, inlet time 9 h) was introduced into the transformer oil-based insulating fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC on H2 in the transformer oil-based insulating fluid, which reached 67.3%.

[0093] Example 8

[0094] The same as Example 1, except that in the preparation of the transformer oil-based insulating fluid, the transformer oil additive and the transformer oil were magnetically stirred at 600 r / min for 20 min.

[0095] H2(gas flow rate 150 mL / min, gas flow time 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic metering instrument, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 56.67%.

[0096] Example 9

[0097] The same as Example 1, except that the calcination was performed in flowing air at 220°C.

[0098] H2(gas flow rate 150 mL / min, gas flow time 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic metering instrument, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 58.56%.

[0099] Example 10

[0100] AC pretreatment: The activated carbon was soaked in a 1.5 mol / L NaOH solution at 60°C for 14 h, the activated carbon and the NaOH solution were used in a mass ratio of 1:2, then washed with deionized water until the pH was 9, and dried at 90°C for 10 h, and then calcined at 700°C under a N2 atmosphere for 1 h to obtain the pretreated activated carbon.

[0101] Pd / AC preparation: 280 mL of a 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 0.5 mL of a 2 wt% PVA solution to obtain a yellow-brown solution, then 0.5 mL of a 0.05 mol / L NaBH4 solution was added dropwise under magnetic stirring at a speed of 900 r / min to obtain a dark brown palladium sol, after stirring for 8 min, the palladium sol was acidified to pH = 7 with concentrated sulfuric acid, then the above-mentioned pretreated activated carbon was added and stirred for 3.5 h, then the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic nano-palladium on the activated carbon 2 wt%, and then washed thoroughly with deionized water until there was no Cl - , then dried at 90°C for 10 h, and then calcined in flowing air at 150°C for 5 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0102] Transformer oil-based insulation fluid preparation: The transformer oil additive was mixed with transformer oil in a mass ratio of 1:12, and then magnetically stirred at 100 r / min for 30 min, and then ultrasonically treated for 1.5 h, and then degassed under a pressure of less than 0.1 kPa for 60 h.

[0103] H2 gas content test

[0104] H2(150 mL / min, 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 56.74%.

[0105] Example 11

[0106] AC pretreatment: The activated carbon was soaked in 0.5 mol / L NaOH solution at 100°C for 10 h, and the mass ratio of activated carbon to NaOH solution was 1:2, then washed with deionized water until pH = 9, and dried at 50°C for 14 h, and then calcined at 300°C under N2 atmosphere for 5 h to obtain the pretreated activated carbon.

[0107] Pd / AC preparation: 220 mL, 0.3 mmol / L Na2PdCl4 aqueous solution was mixed with 2.5 mL, 1.5 wt% PVA solution to obtain a yellow-brown solution, then 2.5 mL, 0.15 mol / L NaBH4 solution was added dropwise under magnetic stirring at a speed of 200 r / min to obtain a dark brown palladium sol, and after stirring for 1 min, the palladium sol was acidified to pH = 1 with concentrated sulfuric acid, then the pretreated activated carbon was added and stirred for 0.5 h, and then the slurry was filtered, and the palladium content on the activated carbon carrier was checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic nano-palladium on the activated carbon 1.5 wt%, and then washed thoroughly with deionized water until there was no Cl - , then dried at 50°C for 14 h, and then calcined in flowing air at 250°C for 1 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0108] Preparation of transformer oil-based insulation fluid: The transformer oil additive was mixed with transformer oil at a mass ratio of 1:12, and stirred at 800 r / min for 5 min, and then ultrasonic for 3 h, and degassed under a pressure of less than 0.1 kPa for 20 h.

[0109] H2 gas content test

[0110] H2(150 mL / min, 9 h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 56.74%.

[0111] Comparative Example 1

[0112] The same as example 1, except that the Pd doping is not performed, and the specific steps are as follows:

[0113] AC pretreatment: the activated carbon is soaked in 1 mol / L NaOH solution at 80°C for 12 h, and the mass ratio of activated carbon to NaOH solution is 1:2, then washed with deionized water until pH = 7, and dried at 70°C for 10-14 h, and then calcined at 500°C under N2 atmosphere for 3 h to obtain the pretreated activated carbon.

[0114] The pretreated AC is mixed with transformer oil according to a mass ratio of 1:12, magnetically stirred at 200 r / min for 5 min, then ultrasonically treated for 1.5 h, and degassed under a pressure of less than 0.1 kPa for 20 h.

[0115] H2 gas content test

[0116] H2 (flow rate 150 mL / min, inlet time 9 h) is introduced into the transformer oil-based insulating fluid prepared in this example using a standard gas automatic meter, and then an oil gas chromatograph is used to analyze the adsorption rate of AC in the transformer oil-based fluid to H2, which reaches 10.08%.

[0117] By comparing comparative example 1 and example 1, it can be seen that the H2 content in the insulating fluid prepared by doping Pd / AC is significantly reduced. It shows that H2 has a very high affinity for metal palladium.

[0118] Comparative example 2

[0119] The same as example 2, except that the drying step in the preparation process of Pd / AC is omitted, and the specific steps are as follows:

[0120] AC pretreatment: the same as example 2.

[0121] Preparation of Pd / AC: 240 mL, 0.3 mmol / L Na2PdCl4 aqueous solution and 1.3 mL, 1 wt% PVA solution are stirred and mixed to obtain a yellow-brown solution, then 1.1 mL, 0.09 mol / L NaBH4 solution is added dropwise under magnetic stirring at a speed of 600 r / min to obtain a dark brown palladium sol, after stirring for 3 min, the palladium sol is acidified to pH = 2 with concentrated sulfuric acid, then the pretreated activated carbon is added and stirred for 1.5 h, then the slurry is filtered, and the palladium content on the activated carbon carrier is checked by inductively coupled plasma mass spectrometry (ICP-MS) analysis to make the loading of monatomic nano-palladium on the activated carbon meet 1 wt%, and then washed thoroughly with deionized water until there is no Cl - , and then calcined at 180°C in a flowing air for 2.5 h to remove the PVA protective agent to obtain a transformer oil additive (Pd / AC).

[0122] Preparation of transformer oil-based insulation fluid: same as example 2.

[0123] H2 gas content test

[0124] H2 (flow rate 150 mL / min, time of passage 9 h) was passed into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 13.87%.

[0125] The drying step in the preparation process of Pd / AC was omitted on the basis of example 2, and the specific reason for the decrease in the adsorption rate of H2 may be that the water competes with the active sites on the surface of the catalyst to reduce the activity if the catalyst is used directly without drying, and some side reactions may occur if the catalyst is not dried, which leads to a decrease in reaction selectivity.

[0126] Comparative example 3

[0127] The same as example 1, except that the degassing step in the preparation process of the transformer oil-based insulation fluid was omitted, specifically:

[0128] AC pretreatment: same as example 1.

[0129] Preparation of Pd / AC: same as example 1.

[0130] Preparation of transformer oil-based insulation fluid: transformer oil additives and transformer oil were mixed in a mass ratio of 1:12, magnetically stirred at 200 r / min for 5 min, and then ultrasonically treated for 1.5 h.

[0131] H2 gas content test

[0132] H2 (flow rate 150 mL / min, time of passage 9 h) was passed into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 14.78%.

[0133] The degassing step was omitted on the basis of example 1, and the specific reason for the decrease in the adsorption rate of H2 may be that degassing can reduce the content of gas in the oil, reduce the occurrence rate of partial discharge, and increase the adsorption rate. On the contrary, if the oil is not degassed, the presence of other gases in the oil will greatly reduce the adsorption rate.

[0134] Comparative example 4

[0135] The same as example 1, except that the loading amount of monatomic nano-palladium on the activated carbon was 0.5 wt%.

[0136] H2 (flow rate 150 mL / min, time 9h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 45.78%.

[0137] Comparative Example 5

[0138] The same as Example 1, except that the loading of monatomic nano-palladium on activated carbon was 4wt%.

[0139] H2 (flow rate 150 mL / min, time 9h) was introduced into the transformer oil-based insulation fluid prepared in this example using a standard gas automatic meter, and then oil gas chromatography was used to analyze the adsorption rate of Pd / AC to H2 in the transformer oil-based insulation fluid, which reached 51.56%.

[0140] From the above examples and comparative examples, it can be seen that the preparation of insulation fluid by doping Pd / AC in transformer oil can improve the adsorption of H2 in transformer oil and eliminate partial discharge failure, which has important significance for alleviating transformer failure and ensuring the safe and stable operation of the transformer.

[0141] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A transformer oil-based insulating fluid, characterized in that, The transformer oil additive is obtained by mixing transformer oil with ultrasonication and degassing; the transformer oil additive is activated carbon loaded with single-atom palladium nanoparticles, and the loading amount of single-atom palladium nanoparticles on the activated carbon is 1-2 wt%. The method for preparing the transformer oil additive includes the following steps: Palladium sol was obtained by mixing and stirring Na2PdCl4 aqueous solution, PVA solution and NaBH4 solution. The palladium sol was acidified with concentrated sulfuric acid, then activated carbon was added and stirred. The mixture was filtered, washed, dried and calcined to obtain the transformer oil additive. The activated carbon needs to be pretreated before being added. The pretreatment steps are as follows: soak the activated carbon in 0.5-1.5 mol / L NaOH solution at 60-100℃ for 10-14 h, then wash it with deionized water until pH=5-9, dry it at 50-90℃ for 10-14 h, and then calcine it at 300-700℃ in N2 atmosphere for 1-5 h.

2. The transformer oil-based insulating fluid according to claim 1, characterized in that, The concentration of the Na2PdCl4 aqueous solution is 0.3 mmol / L, the concentration of the PVA solution is 1.5-2 wt%, and the concentration of the NaBH4 solution is 0.05-0.15 mol / L.

3. The transformer oil-based insulating fluid according to claim 1, characterized in that, The mass ratio of the Na2PdCl4 aqueous solution, PVA solution and NaBH4 solution is (220-280):(0.5-2.5):(0.5-2.5).

4. The transformer oil-based insulating fluid according to claim 1, characterized in that, The palladium sol was acidified with concentrated sulfuric acid to pH 1-7.

5. The transformer oil-based insulating fluid according to claim 1, characterized in that, The drying temperature is 50-90℃, and the time is 10-14 hours.

6. The transformer oil-based insulating fluid according to claim 1, characterized in that, The calcination temperature is 150-250℃, and the time is 1-5h.

7. The transformer oil-based insulating fluid according to claim 1, characterized in that, The degassing pressure is less than 0.1 kPa, and the time is 20-60 h.

8. The application of the transformer oil-based insulating fluid according to any one of claims 1-7 in the hydrogen adsorption of transformer oil.

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