阅读说明：本技术 一种降低天然酯绝缘油倾点的处理方法 (Treatment method for reducing pour point of natural ester insulating oil ) 是由 杨涛 陈上吉 王吉 王震宇 孙鹏 蒲兵舰 马建伟 王天 王伟 周少珍 张嵩阳 于 2019-10-28 设计创作，主要内容包括：本发明提供了一种降低天然酯绝缘油倾点的处理方法,属于天然酯绝缘油深度精炼技术领域。一种降低天然酯绝缘油倾点的处理方法包括结晶分提处理和添加剂添加处理。本方法通过结晶分提处理,大大降低了天然酯绝缘油中高熔点甘油酯和蜡的含量,并与添加剂有效结合可使天然酯绝缘油倾点降至-25℃以下,且保持良好的理化、电气性能,能够满足天然酯绝缘油在我国大部分地区的应用需求。本发明技术优势明显,适用性强,工艺流程简单,生产成本低,完全满足工业化生产的技术需求,具有良好的技术转化和实施前景。(The invention provides a treatment method for reducing the pour point of natural ester insulating oil, and belongs to the technical field of deep refining of natural ester insulating oil. A treatment method for reducing the pour point of natural ester insulating oil comprises crystallization fractionation treatment and additive addition treatment. The method greatly reduces the content of high-melting-point glyceride and wax in the natural ester insulating oil through crystallization fractionation treatment, effectively combines the natural ester insulating oil with additives to reduce the pour point of the natural ester insulating oil to below-25 ℃, keeps good physical, chemical and electrical properties, and can meet the application requirements of the natural ester insulating oil in most areas of China. The method has the advantages of obvious technical advantages, strong applicability, simple process flow and low production cost, completely meets the technical requirements of industrial production, and has good technical transformation and implementation prospects.)

1. A treatment method for reducing the pour point of natural ester insulating oil is characterized by comprising the following steps: the method comprises the following steps of sequentially carrying out crystallization fractionation treatment and additive addition treatment on the natural ester insulating oil, wherein the crystallization fractionation treatment specifically comprises the following steps:

1) heating the natural ester insulating oil to 65-70 ℃ under the vacuum conditions of 60-80 r/min and-0.096-0.1 Mpa, then carrying out short-time ultrasonic oscillation treatment, and continuously stirring for 30-45 min;

2) adjusting the rotating speed to 20-30 r/min, cooling the natural ester insulating oil to 18-22 ℃ in vacuum, and continuously stirring for 60-80 min;

3) maintaining the temperature difference between the cooling medium and the natural ester insulating oil at 8-10 ℃ and stirring at 5-8 r/min, and cooling the natural ester insulating oil to 3-5 ℃ at normal pressure for 8-10 h;

4) and (3) keeping the temperature difference between the cooling medium and the natural ester insulating oil at 4-7 ℃ and stirring at 3-4 r/min, cooling the natural ester insulating oil to-5-3 ℃ at normal pressure, stirring at constant temperature for 18-24 h, and then filtering at constant temperature.

2. The method of claim 1, wherein the pour point of the natural ester insulating oil is reduced by: the natural ester insulating oil is one of soybean insulating oil, rapeseed insulating oil and camellia seed insulating oil.

3. The method of claim 1, wherein the pour point of the natural ester insulating oil is reduced by: the additive addition treatment specifically comprises the following steps: heating the natural ester insulating oil after constant temperature filtration to 70-80 ℃ under the vacuum conditions of 40-50 r/min and-0.096-0.1 Mpa, adding an additive, performing short-time ultrasonic vibration treatment, continuously stirring for 40-60 min, and then cooling the natural ester insulating oil to room temperature in vacuum.

4. The method of claim 1 or 3, wherein the pour point of the natural ester insulating oil is reduced by: the short-time ultrasonic oscillation treatment conditions are as follows: the ultrasonic power is 100-300W, the ultrasonic frequency is 16-20 kHz, the ultrasonic treatment time is 12-30 min, and a circulation mode of ultrasonic oscillation for 1-3 min and stopping for 2-3 min is adopted.

5. The method of claim 3, wherein the pour point of the natural ester insulating oil is reduced by: the additive is an antioxidant and a pour point depressant, the addition mass of the antioxidant is 0.2-0.5% of the mass of the natural ester insulating oil, and the addition mass of the pour point depressant is 0.5-1% of the mass of the natural ester insulating oil.

6. The method of claim 5, wherein the pour point of the natural ester insulating oil is reduced by: the antioxidant is one or more of tert-butyl hydroquinone, tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and 4, 4 methylene (2, 6-di-tert-butylphenol).

7. The method of claim 5, wherein the pour point of the natural ester insulating oil is reduced by: the pour point depressant is one or more of poly-alpha-olefin, polymethacrylate, octyl naphthalene and alcohol ester type maleic anhydride-vinyl acetate-styrene polymer.

Technical Field

The invention belongs to the technical field of deep refining of natural ester insulating oil, and particularly relates to a treatment method for reducing the pour point of the natural ester insulating oil.

Background

The insulating oil is an important liquid insulating medium, is mainly applied to liquid immersion type high-voltage insulating equipment, such as liquid immersion type transformers, circuit breakers, mutual inductors and the like, eliminates insulating air gaps in the electric equipment through immersion and filling, and plays roles in insulating, radiating, cooling and extinguishing electric arcs. The mineral insulating oil has good electrical insulation and cooling performance, is well applied to electrical equipment, but is not suitable for occasions with high requirements on fire safety and environmental protection due to low ignition point and poor biodegradability.

As an environment-friendly novel high-ignition-point liquid insulating medium, natural ester insulating oil (vegetable insulating oil) has incomparable performance advantages compared with mineral insulating oil: the flash point reaches above 300 ℃, and the requirement of the fireproof performance of the electrical equipment is completely met; the biodegradation rate reaches more than 95% in 28 days, and the environmental pollution can be avoided even if the leakage occurs, so that the requirement of environmental protection is met; the renewable energy-saving oil-water separator can effectively relieve the excessive dependence of electrical equipment on oil resources. The natural ester insulating oil is applied to the transformer, so that the transformer has the performance advantages of high ignition point, environmental protection, low noise and the like, the overload capacity of the transformer is improved, the service life of the transformer is prolonged, the technical problems of high load in rural areas and the like are effectively relieved, and the safe and stable operation of a power grid is ensured.

The development of foreign natural ester insulating oil has been over 30 years old, and the oil is widely applied to liquid-immersed transformers, and at present, over 100 thousands of natural ester insulating oil transformers are in operation and are distributed in different industries such as power grids, new energy, ocean wind power, petroleum, railways and the like. China makes a major breakthrough in the aspect of natural ester insulating oil in recent years, the localization of the natural ester insulating oil is successfully realized, and the natural ester insulating oil is applied to distribution transformers in many places such as Henan, Hubei, Shandong and Jiangsu, and plays a good demonstration role.

Due to the molecular constitution of the natural ester insulating oil, the pour point of the natural ester insulating oil is higher than that of the mineral insulating oil (the pour point of rapeseed insulating oil is generally-16 ~ -18 ℃, and the pour point of soybean insulating oil is generally-12 ~ -16 ℃), the lowest environmental temperature of most northern China is lower than-20 ℃, when the environmental temperature is lower than the pour point, the natural ester insulating oil is gradually changed from a liquid state to a solid state, the physical and chemical properties and the electrical properties of the natural ester insulating oil are changed to a certain extent, the pour point of the natural ester insulating oil is improved by a practical and effective method at present, the related technical requirements of cold start of a transformer with the natural ester insulating oil are lacked, the cold start method of the transformer with the mineral insulating oil is not suitable for the transformer with the natural ester insulating oil, the normal start and the operation of the transformer with the natural ester insulating oil under the low-temperature condition cannot be guaranteed.

Chinese patent CN 101538500A discloses a method for preparing insulating oil by using vegetable oil as raw material, which comprises the steps of alkali neutralization, reduced pressure distillation, hydrogenation, deep refining and the like of the vegetable oil, and finally adding additives. Although the oxidation resistance of the insulating oil is improved by the hydrogenation process selected in the method, the saturation degree of the insulating oil is improved to a certain extent, so that the pour point of the insulating oil is increased, and the application prospect of the insulating oil is limited.

Chinese patent CN102682869A discloses a preparation method of vegetable insulating oil, which is prepared by carrying out ester exchange, reduced pressure distillation, decoloration, deacidification, filtration, deep dehydration and other processes on refined vegetable oil and finally adding an additive. The 'ester exchange' process selected in the method can effectively reduce the kinematic viscosity of the vegetable insulating oil, but can reduce the flash point of the vegetable insulating oil, and cannot meet the technical requirements of the vegetable insulating oil, and the addition of the pour point depressant reduces the pour point of the vegetable insulating oil to a certain extent, but cannot meet the use requirements of the vegetable insulating oil in low-temperature areas.

Chinese patent CN101619254A discloses a mixed insulating oil and a preparation method thereof, the mixed insulating oil prepared by the method is mainly mineral insulating oil, and is mixed with vegetable insulating oil in a proper proportion, so that the aging of oil paper insulation can be effectively inhibited. Although the pour point of the insulating oil is effectively improved, the technical requirements of the vegetable insulating oil cannot be met.

Chinese patent CN104987914A discloses a low pour point mixed insulating oil and a preparation method thereof, the mixed insulating oil prepared by the method takes vegetable insulating oil as a main component, and mineral insulating oil with a proper proportion is mixed in the vegetable insulating oil, so that the pour point of the insulating oil can be reduced to about-20 ℃. However, researches show that the content of the mineral insulating oil in the vegetable insulating oil exceeds 10%, so that the ignition point of the vegetable insulating oil is rapidly reduced, the fireproof performance of the vegetable insulating oil is seriously influenced, and the requirements of IEC K-level liquid cannot be met.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a treatment method for reducing the pour point of a natural ester insulating oil, wherein the obtained natural ester insulating oil has excellent physical, chemical and electrical properties, the pour point is below-25 ℃, and the application requirements of the natural ester insulating oil in most areas of China can be met.

The invention also aims to provide the low-pour-point natural ester insulating oil obtained by the treatment method.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the treatment method for reducing the pour point of the natural ester insulating oil sequentially comprises the following steps of carrying out crystallization fractionation treatment and additive addition treatment on the natural ester insulating oil:

1) heating the natural ester insulating oil to 65-70 ℃ under the vacuum conditions of 60-80 r/min and-0.096-0.1 Mpa, then carrying out short-time ultrasonic oscillation treatment, and continuously stirring for 30-45 min;

2) adjusting the rotating speed to 20-30 r/min, cooling the natural ester insulating oil to 18-22 ℃ in vacuum, and continuously stirring for 60-80 min;

3) maintaining the temperature difference between the cooling medium and the natural ester insulating oil at 8-10 ℃ and stirring at 5-8 r/min, and cooling the natural ester insulating oil to 3-5 ℃ at normal pressure for 8-10 h;

4) and (3) keeping the temperature difference between the cooling medium and the natural ester insulating oil at 4-7 ℃ and stirring at 3-4 r/min, cooling the natural ester insulating oil to-5-3 ℃ at normal pressure, stirring at constant temperature for 18-24 h, and then filtering at constant temperature.

Preferably, the natural ester insulating oil is one of soybean insulating oil, rapeseed insulating oil, and camellia seed insulating oil.

Preferably, the additive addition treatment specifically comprises the steps of: heating the natural ester insulating oil after constant temperature filtration to 70-80 ℃ under the vacuum conditions of 40-50 r/min and-0.096-0.1 Mpa, adding an additive, performing short-time ultrasonic vibration treatment, continuously stirring for 40-60 min, and then cooling the natural ester insulating oil to room temperature in vacuum.

Preferably, the short-time ultrasonic oscillation treatment conditions are as follows: the ultrasonic power is 100-300W, the ultrasonic frequency is 16-20 kHz, the ultrasonic treatment time is 12-30 min, and a circulation mode of ultrasonic oscillation for 1-3 min and stopping for 2-3 min is adopted.

Preferably, the additive is an antioxidant and a pour point depressant, the mass of the antioxidant is 0.2-0.5% of the mass of the natural ester insulating oil, and the mass of the pour point depressant is 0.5-1% of the mass of the natural ester insulating oil.

Preferably, the antioxidant is one or more of tert-butylhydroquinone, pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] and 4, 4 methylene (2, 6-di-tert-butylphenol).

Preferably, the pour point depressant is one or more of polyalphaolefin, polymethacrylate, octylnaphthalene, and an alcohol ester type maleic anhydride-vinyl acetate-styrene polymer.

The team has been engaged in the research work of the natural ester insulating oil since 2008, and the first refining production line of the natural ester insulating oil with completely independent intellectual property rights is built in 2014, the annual production capacity reaches 1500 tons, the industrial production of the natural ester insulating oil in China is realized for the first time, and China becomes the country in which the 4 th family masters the technology in the world. Meanwhile, a novel insulating material development and performance evaluation laboratory is built, and the research work in the aspects of production, performance detection, novel process research and development, performance improvement and the like of the natural ester insulating oil is specially carried out.

In order to solve the problem of high pour point of the natural ester insulating oil, a large number of experimental studies are carried out in a laboratory by a team. The pour point of the natural ester insulating oil is improved to a certain extent by carrying out a large amount of process adjustment and parameter control optimization on a natural ester insulating oil refining production line and combining different additives, but the application requirement under the low-temperature condition cannot be met.

Considering that mineral insulating oils have a low pour point and good low temperature fluidity, the team attempts to blend two insulating oils for the purpose of lowering the pour point. Through several times of mixing ratio adjustment and mixing process parameter optimization, the pour point of the natural ester insulating oil can be effectively improved by mixing a certain proportion of mineral insulating oil into the natural ester insulating oil, but the environmental protection property and the fire safety property of the natural ester insulating oil are not highlighted along with the increase of the mixing proportion of the mineral insulating oil. The mixing proportion exceeds 10 percent, the flash point of the natural ester insulating oil is sharply reduced (below 200 ℃) and the requirements of the related standards of the natural ester insulating oil cannot be met.

Aiming at the technical problem of reducing the pour point of the natural ester insulating oil, a team creatively provides a crystallization fractionation process meeting the technical requirements of the natural ester insulating oil through a large amount of data verification, process investigation, technical demonstration and laboratory sample trial production. The better the crystallization fractionation effect, the lower the pour point of the natural ester insulating oil, but the longer the whole cycle and the higher the cost. In addition, the pour point of the natural ester insulating oil is lowered, and the high-melting-point saturated component is reduced, so that the thermal stability is deteriorated. Therefore, the actual technical requirements, the characteristics and the economic cost of the natural ester insulating oil are comprehensively considered, a solution idea of 'crystallization fractionation and additives' is finally creatively adopted, the pour point of the natural ester insulating oil is effectively reduced, the good physical, chemical, electrical and thermal stability characteristics of the natural ester insulating oil can be ensured, and the production cost is reduced.

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

1) according to the invention, the vacuum crystal breaking treatment is carried out on the natural ester insulating oil by adopting a mode of combining vacuum heating and ultrasonic oscillation before the crystallization fractionation treatment, so that the nonuniform and irregular crystals precipitated from the natural ester insulating oil in the refining, storage and transportation processes because the oil temperature is lower than the freezing point of the high-melting glyceride and the wax are effectively broken, and the fractionation effect influenced by the defects of the crystals during the low-temperature crystallization fractionation of the natural ester insulating oil is avoided.

2) According to the invention, through optimized control of conditions such as temperature difference between oil temperature and cooling medium, crystallization temperature, crystallization time, stirring rate and the like in the crystallization fractionation treatment process, crystals in the natural ester insulating oil have good uniformity, stability and filterability, the content of high-melting glyceride and wax in the natural ester insulating oil can be effectively reduced through low-temperature filtration, and the pour point of the natural ester insulating oil can be reduced to below-25 ℃ by combining with a pour point depressant, so that the application requirements of the natural ester insulating oil in most regions in China are met.

3) The method of combining mechanical stirring and ultrasonic oscillation can effectively improve the uniform dispersion degree of the additive in the natural ester insulating oil, and the ultrasonic oscillation power, frequency and time are adjustedThe intermittent control can effectively avoid the additive failure or C generation caused by the cracking of the natural ester insulating oil due to the overlarge ultrasonic oscillation energy₂H₆、C₂H₂And the integral performance of the natural ester insulating oil is effectively ensured due to the problems of combustible organic gas and polar substances.

Detailed Description

In order to better understand the present invention, the following examples are further provided to clearly illustrate the contents of the present invention, but the contents of the present invention are not limited to the following examples. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details.