变压器油高温裂解及油中酸影响机理的反应分子动力学模拟  

Simulation of Reactive Molecular Dynamics of Transformer Oil Pyrolysis at High Temperature and the Influence Mechanism of Acid in Oil

作　　者：王学磊 李庆民[2] 张颖[2] 杨芮[2] 高树国 

机构地区：[1]国网山东省电力公司电力科学研究院,济南250061 [2]华北电力大学电气与电子工程学院,北京102206 [3]河北电力科学研究院,石家庄050021

出　　处：《高电压技术》2017年第1期247-255,共9页High Voltage Engineering

基　　金：国家自然科学基金(51477051);北京市自然科学基金(3142018)~~

摘　　要：变压器油热裂解是其内部绝缘缺陷发生时的主要降解形式之一,以16个C原子数的烃分子为例,引入反应力场(Reax FF)反应分子动力学方法对其高温下的裂解反应及油中酸的影响进行了模拟,从原子层面揭示其微观反应动力学机理。统计不同温度下裂解过程的反应物和生成物变化,结果表明:随着温度升高,3类反应物裂解速度均明显加快;裂解的主要生成物为C2H4、C3H6、CH3、H2、C2H5、C2H6、C2H3等小分子烃或自由基,各温度下C2H4均为数量最多的产物,且在达到饱和之前基本呈线性增长;随着温度的升高,裂解生成的小分子烃的不饱和度增加,H2质量分数也明显增多。对添加甲酸的变压器油裂解过程模拟表明:随着甲酸质量分数的提高,生成H2的数量成正比增加,且其生成量与甲酸的减少量相一致;反应路径分析表明酸性环境下H2的生成主要和甲酸羟基的H与烃类的H发生反应有关,这也是甲酸加速变压器油裂解的原因。Transformer oil pyrolysis is one of the main degradation forms when internal insulation defects happen in transformers. Consequently, in order to reveal the dynamic reaction mechanism at an atomic level,taking hydrocarbon molecules with the same carbon atom number of 16 as transformer oil models, we introduce ReaxFF （reactive force field） to simulate reactive molecular dynamics for transformer oil pyrolysis at high temperature and the influence mechanism of acid in oil. By analyzing the distribution of reactants and products during the pyrolysis process at different temperatures, we find that,as the temperature rises, the cracking rate of all three reactants will speed up significantly; the pyrolysis products are mainly small molecules and radicals, such as C2H4, C3H6, CH3, H2, C2H5, C2H6, and C2H3; C2H4 is the most dominant products and its amount grows linearly until saturated; as temperature rises, the unsaturation degree of the small products increases and the number of H2 increases significantly. By investigating the simulation trajectory of transformer oil pyrolysis added with formic acid, we find that the formation amount of H2 is proportional to the increase of formic ac- id, which is also corresponding to the reduction of formic acid; the reaction paths reveal that, in the acidic conditions, the generation of H is mainly produced by the reaction between hydroxyl H in formic acid and H in hydrocarbons, which is found to be the reason of acceleration pyrolysis mechanism in formic acid for transformer oil.

关 键 词：反应力场 变压器油 甲酸 高温裂解 反应分子动力学 分子模拟 

分 类 号：TM41[电气工程—电器]