Preparation process and device for preparing transformer insulating oil from plant cottonseed oil

Abstract

The invention relates to the technical field of transformer insulating oil preparation, and discloses a preparation process and device for preparing transformer insulating oil from plant cottonseed oil, and the preparation process comprises the following steps: raw material preparation, first adsorption treatment, second adsorption treatment, vacuum degassing treatment, ultrasonic oscillation treatment and high-voltage electrostatic treatment. The insulating oil is prepared by a physical method, so that pollution possibly caused by a chemical method and adverse effects on the performance of the insulating oil are avoided; through cooperation of multiple steps of two-time adsorption treatment, vacuum degassing, ultrasonic oscillation, high-voltage electrostatic treatment and the like, impurities, water, free fatty acid and the like in the cottonseed oil are effectively removed, the purity and stability of the insulating oil are improved, it is guaranteed that the insulating oil is excellent in performance, the use requirement of the transformer insulating oil can be met, and the advantages of environmental protection and sustainable development are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of transformer insulating oil preparation, in particular to a preparation process and device for transformer insulating oil by utilizing plant cottonseed oil. Background Art

[0002] Insulating oil is usually made by adding antioxidants to deeply refined lubricating oil base oil. It is widely used in high-voltage power equipment such as transformers, circuit breakers, oil-filled cables, power capacitors and bushings. Insulating oil impregnates and protects transformers, cables, capacitors, etc. to prevent air or moisture from entering and ensure reliable insulation. Insulating oil also cools power equipment such as transformers. The hot oil is cooled by the radiator and then returns to the transformer body, so that the insulating oil in the box is circulated and cooled to keep the transformer temperature within a certain range. In addition to being an insulating medium, insulating oil also acts as an arc extinguishing medium to prevent the expansion of the arc and cause the arc to be extinguished quickly.

[0003] Transformer insulating oil can be mainly divided into several categories, such as mineral insulating oil, vegetable insulating oil, silicone oil insulating oil, synthetic ester insulating oil and modified insulating oil. However, mineral insulating oil is prone to leakage pollution and poor fire resistance. Silicone oil insulating oil, synthetic ester insulating oil and modified insulating oil have high manufacturing costs. Vegetable insulating oil has become an increasingly hot research topic in the industry. At present, the preparation of vegetable insulating oil mainly uses raw materials such as rapeseed oil and camellia seed oil, while there are few studies on cottonseed oil as raw material. The acid value and other indicators of cottonseed oil are relatively high. The use of a single alkaline catalyst cannot avoid problems such as active site poisoning in the transesterification reaction.

[0004] Chinese patent CN106635432A discloses a method for producing vegetable insulating oil using swill oil, which uses refined swill oil as a main raw material, ethanol as a reaction raw material, KOH or NaOH as a catalyst, and phosphoric acid as a neutralizing agent. The swill oil and ethanol are subjected to ester exchange to reduce the viscosity of the swill oil and remove impurities in the swill oil to obtain high-purity fatty acid ethyl ester; then, fatty acid ethyl ester is used as a main raw material, pentaerythritol as a reaction raw material, monobutyl tin oxide as a catalyst, diatomaceous earth, kaolin, activated carbon as a filter, and nitrogen as a protective gas. The fatty acid ethyl ester reacts with pentaerythritol to obtain high-quality vegetable insulating oil through a refining process.

[0005] Chinese patent CN113817525A discloses a method for preparing natural ester insulating oil, which comprises degumming raw oil including recycled oil to remove phospholipids to reduce the influence of phospholipids on pour point and facilitate the subsequent separation of fatty acids of various components, and then carrying out ester exchange reaction to obtain mixed fatty acid monoesters after impurity removal, and then carrying out solvent crystallization separation to obtain various high-purity single-component fatty acid monoesters, and then carrying out ester exchange reaction with glycerol under the action of a catalyst to obtain various high-purity single-component triglycerides, and after mixing, obtaining natural ester insulating oil with low pour point and condensation point, which can be used in low temperature areas, has low kinematic viscosity, high fluidity and heat dissipation capacity.

[0006] The above patents all adopt chemical process treatment methods.

[0007] With the development of my country's power industry, higher requirements are placed on the performance and environmental protection of transformer insulating oil. Traditional mineral insulating oil has potential hazards such as limited resources, environmental pollution and non-degradability.

[0008] With the increasing emphasis on environmental protection and sustainable development, the use of natural oils to prepare insulating oils has become a research hotspot. However, natural oil cottonseed oil contains impurities, moisture, etc., which will affect its insulating properties, thus requiring an effective physical preparation method. Summary of the invention

[0009] In view of the deficiencies in the prior art, the present invention provides a preparation process and device for preparing transformer insulating oil using plant cottonseed oil, which has the advantages of being prepared by a physical method and avoiding the pollution and adverse effects on the performance of the insulating oil that may be caused by a chemical method.

[0010] To achieve the above object, the present invention provides the following technical solutions: A preparation process for transformer insulating oil using plant cottonseed oil, the steps of which include: Raw material preparation: cottonseed oil is used as the basic raw material; First adsorption treatment: Place the cottonseed oil in a heating device, slowly heat it to 60-70°C, add the first adsorbent, and stir it using a stirring device to fully blend the first adsorbent with the cottonseed oil to absorb impurities, moisture and some free fat; After stirring, filter through a filter with a filtration accuracy of 5-10μm to obtain the filtrate after the first treatment Second adsorption treatment: the filtrate after the first treatment is transferred to another reactor with vacuum heating function, heated to 90-100°C, and the second adsorbent is added. The filtrate after the second adsorbent is added is placed in a device with a vacuum degree of 0.08-0.09Mpa, and the second deep vacuum constant temperature adsorption treatment is carried out. The constant temperature adsorption time is 60-90 minutes; Vacuum degassing treatment: The liquid of the second adsorption treatment is filtered through a vacuum filtration device with a filtration accuracy of 1-5μm, and the filtered cottonseed oil is placed in a vacuum degassing device with a vacuum degree of 50-150Pa, and the temperature is maintained at 60-70℃. The treatment time is 2-4 hours, so that the dissolved gas in the cottonseed oil can fully escape and reduce the potential harm of the gas content to the insulation performance; Ultrasonic vibration treatment: Place the degassed cottonseed oil in an ultrasonic treatment device, set the ultrasonic frequency to 20-50KHz, the power to 300-600W, and the treatment time to 15-30 minutes. Use the cavitation effect of ultrasound to break up the tiny aggregates in the oil and improve the uniformity and stability of the oil. High-voltage electrostatic treatment: The cottonseed oil treated with ultrasound is passed through a high-voltage electrostatic field with an electrostatic field strength of 3-8kV / cm, so that the charged particles in the oil move and aggregate in a directional manner under the action of the electric field, further removing impurities and optimizing the microstructure of the oil, thereby enhancing the insulation performance.

[0011] Preferably, the first adsorbent is a mixture of kaolin, alumina and magnesium sulfate in a ratio of 2:1:1, and the amount used is 1-3% of the mass of cottonseed oil.

[0012] Preferably, the second adsorbent is a mixture of chain starch, graphene oxide and porous Al2O3 in a ratio of 2:1:3, and the amount used is 0.5-1.5% of the mass of the filtrate.

[0013] Preferably: in the high-voltage electrostatic treatment step, the breakdown voltage is not less than 35 kV, the dielectric loss factor does not exceed 0.2% at 20-40°C, and the moisture content is less than 50 ppm.

[0014] A preparation device for preparing transformer insulating oil using plant cottonseed oil, comprising a first adsorption treatment tank, a second adsorption treatment tank, a vacuum degassing tower, an ultrasonic oscillation box and a high-voltage electrostatic treatment tank, wherein each component is connected in sequence through a pipeline; It also includes a mixing mechanism, which is arranged inside the first adsorption treatment tank and the second adsorption treatment tank, and is used to stir the adsorbent and cottonseed oil inside the first adsorption treatment tank and the second adsorption treatment tank; The mixing mechanism includes an outer shaft and an output shaft, the output shaft is fixedly connected to the inside of the outer shaft, the first adsorption treatment tank and the second adsorption treatment tank include a tank bottom plate, the outer shaft is rotatably connected to the top of the tank bottom plate, the top of the output shaft is hinged with a first stirring rod, the bottom of the first stirring rod is fixedly connected with an auxiliary scraper, the top of the rod body of the first stirring rod is fixedly connected with a guide plate, and a variable frequency motor is arranged on the outside of the output shaft.

[0015] Preferably: a regulator is fixedly connected to the bottom of the tank bottom plate, an inner cavity and an outer cavity are provided inside the regulator, a connecting cavity is provided between the inner cavity and the outer cavity, a feed pipe is fixedly connected to the outside of the inner cavity, the feed pipe is externally connected to an adsorbent supply device, a diverter pipe is fixedly connected to the outside of the inner cavity, a discharge pipe is fixedly connected to the end of the diverter pipe, and a discharge port of the discharge pipe is arranged above the tank body.

[0016] Preferably, the interior of the connecting cavity is movably connected to a control valve ring, the control valve ring extends to the outer end of the regulator and is fixedly connected to a connecting ring, and the outer end of the connecting ring is rotatably connected to a regulating rod.

[0017] Preferably: the regulating rod passes through and is slidably connected to the inside of the outer shaft rod, a return spring is arranged between the regulating rod and the outer shaft rod, the regulating rod is in the shape of a "7", the end of the regulating rod located inside the tank body is slidably connected to the first stirring rod, a positioning ring is arranged at one end of the regulating rod located at the bottom of the tank bottom plate, and the regulating rod is rotatably connected through the positioning ring and the connecting ring.

[0018] Preferably, a weighted ball is fixedly connected to the outside of the first stirring rod, and the auxiliary scraper is attached to the top of the tank bottom plate.

[0019] Preferably, the auxiliary scraper is arranged to be horizontally deflected, an extension plate is slidably connected inside the auxiliary scraper, and a pressure spring is arranged between the extension plate and the auxiliary scraper.

[0020] Beneficial effects of the present invention: 1. The preparation process of transformer insulating oil using plant cottonseed oil is prepared by physical methods, avoiding the pollution and adverse effects on the performance of insulating oil that may be caused by chemical methods; through the coordination of multiple steps such as two adsorption treatments, vacuum degassing, ultrasonic vibration and high-voltage electrostatic treatment, impurities, moisture and free fatty acids in cottonseed oil are effectively removed, the purity and stability of the insulating oil are improved, the insulating oil is guaranteed to have excellent performance, can meet the use requirements of transformer insulating oil, and has the advantages of environmental protection and sustainable development.

[0021] 2. The preparation device for transformer insulating oil using plant cottonseed oil uses a first stirring rod and an auxiliary scraper. The first stirring rod and the auxiliary scraper have different shapes under high-speed rotation and low-speed rotation. Under high-speed rotation, the first stirring rod and the auxiliary scraper expand outward to effectively improve the stirring effect and quickly disperse the adsorbent. Under low-speed rotation, the scraper fits the bottom plate of the tank, reduces energy consumption at low rotation speed, and avoids the influence of excessive stirring on oil quality. At the same time, the scraper can effectively prevent the adsorbent from sinking to the bottom.

[0022] 3. The preparation device for preparing transformer insulating oil using plant cottonseed oil, through the inclined setting of the guide plate and the auxiliary scraper, makes the cottonseed oil form a spiral ascending or descending flow path, thereby increasing the contact frequency and contact effect between the cottonseed oil and the adsorbent, and when the auxiliary scraper is attached to the bottom plate of the tank, the auxiliary scraper pushes the cottonseed oil to diffuse and flow outward, further improving the treatment effect on the precipitated adsorbent, and at the same time facilitating the discharge of the cottonseed oil through the discharge pipe.

[0023] 4. The preparation process and device for preparing transformer insulating oil using plant cottonseed oil, through the cooperation of the auxiliary scraper and the extension plate, when the auxiliary scraper expands outward, the extension plate increases the lateral cross-section of the auxiliary scraper, thereby improving the stirring and diversion effects of the auxiliary scraper, so that the cottonseed oil can form a stable upward spiral flow path, and when the auxiliary scraper is attached to the bottom plate of the tank, the extension plate is converged inside the auxiliary scraper, reducing the lateral cross-section of the auxiliary scraper, reducing the mixing and stirring damping, and avoiding damage to the oil quality due to excessive stirring, thereby ensuring the mixed adsorption effect of the adsorbent and cottonseed oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the overall equipment of the preparation device of the present invention; Figure 2 It is a schematic diagram of the mixing mechanism of the present invention; Figure 3 This is a schematic diagram of the connection between the outer shaft, the output shaft, the first stirring rod, the regulating rod and the regulator of the present invention; Figure 4 This is a schematic diagram of the connection between the first stirring rod and the auxiliary scraper of the present invention; Figure 5 This is a schematic diagram of the connection between the control rod, the connecting ring and the control valve ring of the present invention; Figure 6 This is a schematic diagram of a cross-sectional view of the controller of the present invention; Figure 7 For the present invention Figure 4 An enlarged schematic diagram of part A.

[0025] In the figure: 1. first adsorption treatment tank; 2. second adsorption treatment tank; 3. vacuum degassing tower; 4. ultrasonic oscillation box; 5. high-voltage electrostatic processor tank; 6. mixing mechanism; 61. outer shaft; 62. output shaft; 63. first stirring rod; 64. auxiliary scraper; 641. extension plate; 642. pressure spring; 65. guide plate; 66. counterweight ball; 67. regulator; 68. inner cavity; 69. outer cavity; 610. connecting cavity; 611. feed pipe; 612. diverter pipe; 613. control valve ring; 614. connecting ring; 615. regulating rod; 616. discharge pipe; 617. tank bottom plate; 618. discharge pipe; 619. reset spring. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] A preparation process for transformer insulating oil using plant cottonseed oil, the steps of which include: Raw material preparation: cottonseed oil is used as the basic raw material; First adsorption treatment: Place the cottonseed oil in a heating device, slowly heat it to 60-70°C, add the first adsorbent, and stir it using a stirring device to fully blend the first adsorbent with the cottonseed oil to absorb impurities, moisture and some free fat; After stirring, filter through a filter with a filtration accuracy of 5-10μm to obtain the filtrate after the first treatment Second adsorption treatment: the filtrate after the first treatment is transferred to another reactor with vacuum heating function, heated to 90-100°C, and the second adsorbent is added. The filtrate after the second adsorbent is added is placed in a device with a vacuum degree of 0.08-0.09Mpa, and the second deep vacuum constant temperature adsorption treatment is carried out. The constant temperature adsorption time is 60-90 minutes; Vacuum degassing treatment: The liquid of the second adsorption treatment is filtered through a vacuum filtration device with a filtration accuracy of 1-5μm, and the filtered cottonseed oil is placed in a vacuum degassing device with a vacuum degree of 50-150Pa, and the temperature is maintained at 60-70℃. The treatment time is 2-4 hours, so that the dissolved gas in the cottonseed oil can fully escape and reduce the potential harm of the gas content to the insulation performance; Ultrasonic vibration treatment: Place the degassed cottonseed oil in an ultrasonic treatment device, set the ultrasonic frequency to 20-50KHz, the power to 300-600W, and the treatment time to 15-30 minutes. Use the cavitation effect of ultrasound to break up the tiny aggregates in the oil and improve the uniformity and stability of the oil. High-voltage electrostatic treatment: The cottonseed oil treated with ultrasound is passed through a high-voltage electrostatic field with an electrostatic field strength of 3-8kV / cm, so that the charged particles in the oil move and aggregate in a directional manner under the action of the electric field, further removing impurities and optimizing the microstructure of the oil, thereby enhancing the insulation performance.

[0028] The first adsorbent is a mixture of kaolin, alumina and magnesium sulfate in a ratio of 2:1:1, and the amount used is 1-3% of the mass of cottonseed oil.

[0029] The second adsorbent is a mixture of chain starch, graphene oxide and porous Al2O3 in a ratio of 2:1:3, and the amount used is 0.5-1.5% of the mass of the filtrate.

[0030] Wherein, in the high-voltage electrostatic treatment step, the breakdown voltage is not less than 35 kV, the dielectric loss factor does not exceed 0.2% at 20-40° C., and the moisture content is less than 50 ppm.

[0031] In the adsorption treatment step, the first adsorption uses a mixed adsorbent of kaolin, alumina and magnesium sulfate, and the second adsorption uses a mixed adsorbent of chain starch, graphene oxide and porous Al2O3. These adsorbents have porous structures or active characteristics. Under certain temperature, vacuum and other conditions, they can adsorb impurities, moisture and acidic substances in cottonseed oil, and remove the adsorbent after adsorbing impurities through a filter, thereby achieving the purpose of purification.

[0032] During the vacuum degassing treatment, the vacuum environment and appropriate temperature are used to make the dissolved gas in the cottonseed oil overflow under low pressure, while the ultrasonic vibration treatment uses the cavitation effect to break up the tiny clusters and further optimize the microstructure. The performance of the cottonseed oil is improved through the synergistic effect of the above steps.

[0033] The physical method of preparation avoids the possible pollution and adverse effects on the performance of insulating oil caused by chemical methods.

[0034] Through the coordinated efforts of multiple steps including double adsorption treatment, vacuum degassing, ultrasonic vibration and high-voltage electrostatic treatment, impurities, moisture and free fatty acids in cottonseed oil are effectively removed, thereby improving the purity and stability of the insulating oil and ensuring the excellent performance of the insulating oil. It can meet the use requirements of transformer insulating oil and has the advantages of environmental protection and sustainable development.

[0035] Example 1: 1. Raw material preparation: Select 1000g of high-quality cottonseed oil 2. The first adsorption treatment: Place the cottonseed oil in a heating device, raise the temperature to 60°C, add 10g of adsorbent (1% of the mass of the cottonseed oil) mixed with kaolin, calcium oxide and magnesium sulfate in a ratio of 2:1:1, and use a higher speed (300-400r / min) during the addition of the adsorbent to quickly disperse the adsorbent; after the adsorption reaction has been carried out for 10 minutes, reduce the speed (150-200r / min) to reduce energy consumption and avoid excessive stirring to affect the oil quality, continue stirring for 30 minutes, and then filter with a filter with a filtration accuracy of 5μm.

[0036] 3. For the second adsorption treatment, the filtrate was transferred to a vacuum heating reactor, heated to 90°C, and 5 g of an adsorbent (0.5% by mass of cottonseed oil) of a mixture of amylose, graphene oxide and porous Al2O3 in a ratio of 2:1:3 was added, and adsorbed at a constant temperature for 60 minutes at a vacuum degree of 0.08 MPa, and then filtered using a vacuum filtration device with a filter mesh accuracy of 1 μm.

[0037] 4. Vacuum degassing treatment: Place the filtered cottonseed oil in a vacuum degassing device at a vacuum degree of 50Pa and a temperature of 60°C for 2 hours.

[0038] 5. Ultrasonic vibration treatment: Place the cottonseed oil in an ultrasonic treatment device, set the frequency to 20KHz, the power to 300W, and treat for 15 minutes.

[0039] High-voltage electrostatic field treatment: The cottonseed oil is passed through a high-voltage electrostatic field with an intensity of 3 kV / cm.

[0040] Implementation case 2; 1. Raw material preparation: 2000g high-quality cottonseed oil 2. First adsorption treatment: raise the temperature to 65°C in a heating device, add 40g of the above-mentioned adsorbent (accounting for 2% of the mass of cottonseed oil), and during the addition of the adsorbent, use a higher speed (350-420r / min) to quickly disperse the adsorbent; after the adsorption reaction has been carried out for 15 minutes, reduce the speed (200-250r / min) to reduce energy consumption and avoid excessive stirring to affect the oil quality, continue stirring for 45 minutes, and filter with a filter with a filtration accuracy of 8μm.

[0041] 3. Second adsorption treatment: The filtrate was heated to 95°C in the reactor, 20 g of adsorbent (accounting for 1% of the cottonseed oil) was added, and adsorbed at a constant temperature for 75 minutes under a vacuum degree of 0.085 MPa, and filtered using a vacuum filtration device with a filtration accuracy of 3 μm.

[0042] 4. Vacuum degassing treatment: Cottonseed oil is treated at a vacuum degree of 100Pa and a temperature of 65°C for 3 hours.

[0043] 5. Ultrasonic vibration treatment: ultrasonic frequency 30KHz, power 450W, treatment for 20 minutes.

[0044] 6. High-voltage electrostatic field treatment: through a high-voltage electrostatic field with an intensity of 5kV / cm.

[0045] Implementation case 3: 1. Raw material preparation: 1500g high-quality cottonseed oil 2. The first adsorption treatment: heat to 70 ° C, add 30g of adsorbent (accounting for 2% of the mass of cottonseed oil), and use a higher speed (380-450r / min) during the addition of the adsorbent to disperse the adsorbent quickly; after the adsorption reaction has been carried out for 15 minutes, reduce the speed (200-300r / min) to reduce energy consumption and avoid excessive stirring to affect the oil quality. Continue stirring for 60 minutes and filter with a filter with a filtration accuracy of 10μm.

[0046] 3. Second adsorption treatment: The filtrate was heated to 100°C, 18 g of adsorbent (accounting for 1.2% of the mass of cottonseed oil) was added, and adsorbed at a constant temperature for 90 minutes under a vacuum degree of 0.09 MPa, and filtered using a vacuum filtration device with a filtration accuracy of 5 μm.

[0047] 4. Vacuum degassing treatment: vacuum 150Pa, temperature 70℃ for 4 hours.

[0048] 5. Ultrasonic vibration treatment: ultrasonic frequency 50KHz, power 600w, treatment for 30 minutes.

[0049] High-voltage electrostatic field treatment: through a high-voltage electrostatic field with an intensity of 8kV / cm.

[0050] Implementation Case 4: 1. Raw material preparation: 3000g high-quality cottonseed oil.

[0051] 2. First adsorption treatment: raise the temperature to 68°C, add 60g of adsorbent (accounting for 2% of the mass of cottonseed oil), and during the addition of the adsorbent, use a higher speed (350-420r / min) to disperse the adsorbent quickly; after the adsorption reaction has been carried out for 12 minutes, reduce the speed (180-280r / min) to reduce energy consumption and avoid excessive stirring to affect the oil quality, continue stirring for 50 minutes, and filter with an 8μm filter.

[0052] 3. Second adsorption treatment: the filtrate was heated to 98°C, 30 g of adsorbent (accounting for 1% of the cottonseed oil) was added, and adsorbed at a constant temperature for 80 minutes under a vacuum of 0.088 MPa, and filtered with a 4 μm vacuum filtration device.

[0053] 4. Vacuum degassing treatment: treat at a vacuum degree of 120Pa and a temperature of 68°C for 3.5 hours.

[0054] 5. Ultrasonic vibration treatment: frequency 40KHz, power 500W, treatment for 25 minutes.

[0055] 6. High-voltage electrostatic field treatment: through a high-voltage electrostatic field with an intensity of 6kV / cm.

[0056] Basic numerical conditions of embodiments 1, 2, 3, and 4:

[0057]

[0058] Performance parameters of cottonseed insulating oil

[0059] As can be seen from the above table, the physical preparation of cottonseed insulating oil of the present invention has excellent indicators, among which the breakdown voltage (70kV, 2.5mm), flash point (302°C) and ignition point (330°C) are far better than mineral oil, and the use safety is good; and the low temperature performance is excellent (pour point -37°C).

[0060] Furthermore, in the above embodiment, the preparation process of transformer insulating oil using plant cottonseed oil is carried out by a preparation device for transformer insulating oil using plant cottonseed oil, specifically: refer to Figure 1-Figure 6 , a preparation device for preparing transformer insulating oil using plant cottonseed oil, comprising a first adsorption treatment tank 1, a second adsorption treatment tank 2, a vacuum degassing tower 3, an ultrasonic oscillation box 4 and a high-voltage electrostatic treatment tank 5, each component being connected in sequence through a pipeline; Among them, the first adsorption treatment, the second adsorption treatment, the vacuum degassing treatment, the ultrasonic vibration treatment and the high-voltage electrostatic treatment are carried out in the first adsorption treatment tank 1, the second adsorption treatment tank 2, the vacuum degassing tower 3, the ultrasonic vibration box 4 and the high-voltage electrostatic treatment tank 5 respectively.

[0061] The device further includes a mixing mechanism 6, which is disposed inside the first adsorption treatment tank 1 and the second adsorption treatment tank 2, and is used for stirring the adsorbent and cottonseed oil inside the first adsorption treatment tank 1 and the second adsorption treatment tank 2; The mixing mechanism 6 includes an outer shaft 61 and an output shaft 62. The output shaft 62 is fixedly connected to the inside of the outer shaft 61. The first adsorption treatment tank 1 and the second adsorption treatment tank 2 include a tank bottom plate 617. The outer shaft 61 is rotatably connected to the top of the tank bottom plate 617. The top of the output shaft 62 is hinged with a first stirring rod 63. The bottom of the first stirring rod 63 is fixedly connected with an auxiliary scraper 64. The top of the rod body of the first stirring rod 63 is fixedly connected with a guide plate 65. A variable frequency motor is arranged on the outside of the output shaft 62.

[0062] It should be noted that the variable frequency motor can flexibly adjust the stirring speed according to the amount of filtrate, adsorbent characteristics and reaction stage. During the addition of adsorbent, a higher speed (300-450r / min) is used to quickly disperse the adsorbent; after the adsorption reaction has been going on for a period of time, the speed is reduced (150-300r / min) to reduce energy consumption and avoid excessive stirring that affects the oil quality.

[0063] It should be noted that a guide plate 65 is arranged outside the first stirring rod 63, and the guide plate 65 is arranged at an angle. When the guide plate 65 rotates with the first stirring rod 63, the guide plate 65 makes the cottonseed oil form a spiral upward or downward flow path, thereby increasing the contact frequency and contact effect between the cottonseed oil and the adsorbent.

[0064] Among them, a regulator 67 is fixedly connected to the bottom of the tank bottom plate 617, an inner cavity 68 and an outer cavity 69 are opened inside the regulator 67, a connecting cavity 610 is opened between the inner cavity 68 and the outer cavity 69, a feed pipe 611 is fixedly connected to the outside of the inner cavity 68, the feed pipe 611 is externally connected to the adsorbent supply equipment, a diverter pipe 612 is fixedly connected to the outside of the inner cavity 68, a discharge pipe 616 is fixedly connected to the end of the diverter pipe 612, and a discharge port of the discharge pipe 616 is arranged above the tank body.

[0065] It should be noted that when the adsorbent is added, the adsorbent is first added to the inner cavity 68 through the delivery pipe 611 , and the adsorbent enters the outer cavity 69 through the connecting cavity 610 under pressure, and then dispersed to a plurality of discharge pipes 616 through the diversion pipe 612 .

[0066] By dispersing and spraying the adsorbent, the adsorbent is dispersed and slowly mixed into the plant cottonseed oil, thereby avoiding the adsorbent from agglomerating inside the cottonseed oil, thereby ensuring the initial mixing effect of the adsorbent and the cottonseed oil, facilitating the subsequent mixing and adsorption effect, and thus improving the adsorption effect on the cottonseed oil.

[0067] The connection cavity 610 is internally movably connected to a control valve ring 613 , the control valve ring 613 extends to the outer end of the regulator 67 and is fixedly connected to a connection ring 614 , and the outer end of the connection ring 614 is rotatably connected to a control rod 615 .

[0068] Among them, the regulating rod 615 passes through and is slidably connected to the inside of the outer shaft rod 61, a return spring 619 is arranged between the regulating rod 615 and the outer shaft rod 61, the regulating rod 615 is in a "7" shape, and the end of the regulating rod 615 located inside the tank body is slidably connected to the first stirring rod 63, and a positioning ring is arranged at one end of the regulating rod 615 located at the bottom of the tank bottom plate 617, and the regulating rod 615 is rotatably connected through the positioning ring and the connecting ring 614.

[0069] The first stirring rod 63 is fixedly connected to the outside with a weighted ball 66 , and the auxiliary scraper 64 is attached to the top of the tank bottom plate 617 .

[0070] It should be noted that during the addition of the adsorbent, the variable frequency motor controls the output shaft 62 to rotate at high speed, and the output shaft 62 drives the first stirring rod 63 to rotate at high speed, so that under the action of centrifugal force, the first stirring rod 63 is offset upward, and the first stirring rod 63 drives the regulating rod 615 to move upward, and the regulating rod 615 drives the control valve ring 613 to move upward through the bottom connecting ring 614, so that the outer cavity 69 and the connecting cavity 610 are connected, and the inner cavity 68 and the outer cavity 69 are connected, so that the adsorbent can enter the discharge pipe 616 through the outer cavity 69 and the diverter pipe 612 to disperse and add the adsorbent.

[0071] During the high-speed stirring stage, the first stirring rod 63 expands outward, thereby effectively increasing the stirring range of the first stirring rod 63, and at this time the auxiliary scraper 64 is laterally suspended in the adsorption tank to assist in increasing the stirring effect and further improve the mixing effect of the initial contact between the adsorbent and the cottonseed oil.

[0072] During the mixing stage, the frequency conversion motor controls the output shaft 62 to reduce its rotation speed, and the centrifugal force of the first stirring rod 63 and the counterweight ball 66 is reduced. Under the action of the return spring 619, the offset amplitude of the first stirring rod 63 is reduced, so that the auxiliary scraper 64 fits against the top of the tank bottom plate 617, thereby ensuring that during the low-speed mixing and adsorption period, excessive stirring can avoid damage to the oil quality, and the auxiliary scraper 64 can effectively prevent the adsorbent from settling, further ensuring the mixed adsorption effect of the adsorbent and cottonseed oil.

[0073] Furthermore, the auxiliary scraper 64 is arranged to be horizontally deflected, and an extension plate 641 is slidably connected inside the auxiliary scraper 64 , and a pressure spring 642 is arranged between the extension plate 641 and the auxiliary scraper 64 .

[0074] The auxiliary scraper 64 is deflected, so when the first stirring rod 63 expands outward, the auxiliary scraper 64 is synchronously deflected outward, and at this time the extension plate 641 extends outward under the action of the pressure spring 642, thereby increasing the cross-section of the auxiliary scraper 64, increasing the stirring and mixing effect of the auxiliary scraper 64 on the cottonseed oil, and the auxiliary scraper 64 is deflected, so when the auxiliary scraper 64 rotates, the cottonseed oil produces an upward spiral flow path, thereby further improving the mixing effect of the auxiliary scraper 64 on the cottonseed oil.

[0075] Furthermore, when the first stirring rod 63 rotates at a low speed, the regulating rod 615 moves downward under the action of the reset spring 619, and the control valve ring 613 moves downward to cut off the connecting chamber 610 and the outer chamber 69, and stops the adsorbent from being added under the low speed rotation, and at the same time, ensures the mixed adsorption effect of the adsorbent cottonseed oil under the low speed rotation. When the regulating rod 615 moves downward, the first stirring rod 63 deflects downward, and at the same time, the auxiliary scraper 64 fits the tank bottom plate 617, and at this time, the extension plate 641 compresses the pressure spring 642 to the inside of the auxiliary scraper 64, and at the same time, because the auxiliary scraper 64 is tilted, the auxiliary scraper 64 pushes the cottonseed oil to diffuse and flow outward, further improving the treatment effect of the precipitated adsorbent, and at the same time, it is convenient for the cottonseed oil to be discharged through the discharge pipe 618.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing transformer insulating oil using plant cottonseed oil, characterized in that: The steps include: Raw material preparation: cottonseed oil is used as the basic raw material; First adsorption treatment: Place the cottonseed oil in a heating device, slowly heat it to 60-70°C, add the first adsorbent, and stir it with a stirring device to fully blend the first adsorbent with the cottonseed oil; Second adsorption treatment: the filtrate after the first adsorption treatment is transferred to another reactor with vacuum heating function, heated to 90-100°C, and the second adsorbent is added. The filtrate after the second adsorbent is added is placed in a device with a vacuum degree of 0.08-0.09Mpa, and the second deep vacuum constant temperature adsorption treatment is carried out. The constant temperature adsorption time is 60-90 minutes; Vacuum degassing treatment: The liquid subjected to the second adsorption treatment is filtered through a vacuum filtration device with a filtration accuracy of 1-5 μm, and the filtered cottonseed oil is placed in a vacuum degassing device with a vacuum degree of 50-150 Pa, the temperature is maintained at 60-70°C, and the treatment time is 2-4 hours; Ultrasonic vibration treatment: Place the degassed cottonseed oil in an ultrasonic treatment device, set the ultrasonic frequency to 20-50KHz, the power to 300-600W, and the treatment time to 15-30 minutes; High-voltage electrostatic treatment: The cottonseed oil treated with ultrasound is passed through a high-voltage electrostatic field with an electrostatic field strength of 3-8kV / cm, so that the charged particles in the oil move and aggregate in a directional manner under the action of the electric field.

2. A process for preparing transformer insulating oil using plant cottonseed oil according to claim 1, characterized in that: The first adsorbent is prepared by mixing kaolin, alumina and magnesium sulfate in a ratio of 2:1:1, and the amount used is 1-3% of the mass of cottonseed oil.

3. A process for preparing transformer insulating oil by using plant cottonseed oil according to claim 1, characterized in that: The second adsorbent is a mixture of chain starch, graphene oxide and porous Al2O3 in a ratio of 2:1:3, and the amount used is 0.5-1.5% of the mass of the filtrate.

4. A process for preparing transformer insulating oil using plant cottonseed oil according to claim 1, characterized in that: In the high-voltage electrostatic treatment step, the breakdown voltage is not less than 35 kV, the dielectric loss factor does not exceed 0.2% at 20-40° C., and the moisture content is less than 50 ppm.

5. A preparation device for preparing transformer insulating oil using plant cottonseed oil, used for preparing the transformer insulating oil prepared using plant cottonseed oil according to any one of claims 1 to 4, characterized in that: It includes a first adsorption treatment tank, a second adsorption treatment tank, a vacuum degassing tower, an ultrasonic oscillation box and a high-voltage electrostatic treatment tank, and each component is connected in sequence through pipelines; It also includes a mixing mechanism, which is arranged inside the first adsorption treatment tank and the second adsorption treatment tank, and is used to stir the adsorbent and cottonseed oil inside the first adsorption treatment tank and the second adsorption treatment tank; The mixing mechanism includes an outer shaft and an output shaft, the output shaft is fixedly connected to the inside of the outer shaft, the first adsorption treatment tank and the second adsorption treatment tank include a tank bottom plate, the outer shaft is rotatably connected to the top of the tank bottom plate, the top of the output shaft is hinged with a first stirring rod, the bottom of the first stirring rod is fixedly connected with an auxiliary scraper, the top of the rod body of the first stirring rod is fixedly connected with a guide plate, and a variable frequency motor is arranged on the outside of the output shaft.

6. The device for preparing transformer insulating oil by using plant cottonseed oil according to claim 5, characterized in that: A regulator is fixedly connected to the bottom of the tank bottom plate, an inner cavity and an outer cavity are provided inside the regulator, a connecting cavity is provided between the inner cavity and the outer cavity, a feed pipe is fixedly connected to the outside of the inner cavity, the feed pipe is externally connected to an adsorbent supply device, a shunt pipe is fixedly connected to the outside of the inner cavity, a discharge pipe is fixedly connected to the end of the shunt pipe, and a discharge port of the discharge pipe is arranged above the tank body.

7. The device for preparing transformer insulating oil by using plant cottonseed oil according to claim 6, characterized in that: The interior of the connecting cavity is movably connected with a control valve ring, the control valve ring extends to the outer end of the regulator and is fixedly connected with a connecting ring, and the outer end of the connecting ring is rotatably connected with a regulating rod.

8. The device for preparing transformer insulating oil by using plant cottonseed oil according to claim 7, characterized in that: The regulating rod passes through and is slidably connected to the inside of the outer shaft rod, a return spring is arranged between the regulating rod and the outer shaft rod, the regulating rod is in the shape of a "7", the end of the regulating rod located inside the tank body is slidably connected to the first stirring rod, and a positioning ring is arranged at one end of the regulating rod located at the bottom of the tank bottom plate, and the regulating rod is rotatably connected through the positioning ring and the connecting ring.

9. The device for preparing transformer insulating oil by using plant cottonseed oil according to claim 8, characterized in that: A counterweight ball is fixedly connected to the outside of the first stirring rod, and the auxiliary scraper is attached to the top of the tank bottom plate.

10. The device for preparing transformer insulating oil by using plant cottonseed oil according to claim 8, characterized in that: The auxiliary scraper is arranged to be horizontally deflected, an extension plate is slidably connected inside the auxiliary scraper, and a pressure spring is arranged between the extension plate and the auxiliary scraper.

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