实沸点蒸馏对2种高酸原油腐蚀性的影响及表征

Effect of True Boiling Point Distillation on the Corrosivity of Two Kinds of High-Acid Crude Oils and Its Characterization

高酸原油经实沸点蒸馏后酸值会发生较大程度的损失,哪些类型的石油酸发生了损失及高酸原油腐蚀性是否同等降低却不得而知。针对这一问题,对2种典型高酸原油实沸点蒸馏前后的酸值和腐蚀性进行了考察,并对蒸馏前后高酸原油中的石油酸进行了质谱表征。结果表明:2种高酸原油实沸点蒸馏后液相腐蚀速率减小,而气相腐蚀速率明显增大,说明大分子石油酸分解成了沸点较低的小分子石油酸;2种高酸原油的气、液总腐蚀速率降低都远小于酸值的损失,说明分解生成的小分子石油酸的腐蚀性更强;2种高酸原油实沸点蒸馏前后石油酸的类型变化不大,但碳数分布变化明显,碳数越高的大分子石油酸分解越多。高酸原油的腐蚀性与酸值并非线性关系,石油酸的类型即脂肪酸和一环环烷酸含量可能是影响高酸原油腐蚀性的重要因素。

The acid value of high-acid crude oil will be greatly reduced after true boiling point distillation,but it is unknown which types of petroleum acids have been lost and whether the corrosivity of high-acid crude oils has been reduced equally.In view of this,the acid value and corrosivity of two kinds of typical high-acid crude oils before and after true boiling point distillation were investigated,and the petroleum acid in high-acid crude oils before and after distillation was characterized by MS.The results show that the liquid-phase corrosion rate of the two kinds of high-acid crude oils decreased while the gas-phase corrosion rate increased obviously after true boiling point distillation,indicating the decomposition of macro-molecular petroleum acid into small-molecular petroleum acid.The decrease in the total gas-liquid corrosion rate of the two kinds of high-acid crude oils is much less than the loss of acid value,indicating that the decomposed small-molecular petroleum acid is more corrosive.The types of petroleum acids remain little changed before and after true boiling point distillation of the two kinds of high-acid crude oils,but the carbon number distribution shows an obvious change,suggesting that the higher the carbon number,the greater the decomposition rate of macro-molecular petroleum acid.In addition,the corrosivity of high acid crude oils is not linear with acid value,and the type of petroleum acid,i.e.,the content of fatty acid and monocyclic naphthenic acid,may be a key factor affecting corrosivity.