有机氯化物在原油蒸馏过程中的转移及转化规律研究

Organochlorine compounds (OCC) in crude oil, which could not be removed by eletro-desalting pretreatment, may lead to equipment corrosion, pipeline blockage, and catalyst poisoning. Their existence greatly threatens the security of the crude oil processing units in refinery. In this project, labarotary true-boiling-point distillation is used to simulate crude oil distillation process in refinery. The pretreated crude oil is cut into a series of narrow fractions with various boiling ranges. The distributions of the organically bound chlorine (OBC) and inorganic chlorine in the fractions is determined by various analysis. Based on an establised method to concentrate the organochlorine compounds in crude oil fractions with high-boiling range, their chemical components are thus capable of being identified by GC, GC/MS and other analytical equipments. The molecular structure and size of the organochlorine compounds can be obtained by molecular simulation and quantum chemistry calculation, and their structural stability can be analyzed in molecular scale. Furthermore, the possible chemical reactions involved organochlorine compounds in crude oil distillation as well as the relationship between crude distillation unit corrosion and the chemical reactions could be predicted and discussed by atomic matrix method. Based on these research results, the mass transfer and conversion regulation of organochlorine compounds in crude oil distillation can be determined, meanwhile, the potential damages caused by organochlorine compounds in downstream crude processing units can be predicted.

原油中的有机氯化物无法经电脱盐预处理过程脱除，继而造成设备腐蚀、管线堵塞及催化剂中毒，严重威胁炼厂原油加工装置的生产安全。本项目拟利用实沸点蒸馏模拟炼厂原油蒸馏过程，将脱盐预处理后的原油切割成一系列窄馏分油，并确定原油中无机氯和有机氯在馏分油中的分布规律；建立高沸点馏分油中有机氯化物的富集方法，并借助色谱和色质联用等分析手段鉴定馏分油或其富集物中有机氯化物的化学组成；通过分子模拟和量子化学确定有机氯化物的分子结构及分子尺寸，从分子尺度考察其结构稳定性；利用原子矩阵法分析原油蒸馏过程中有机氯化物发生的反应类型，分析有机氯化物腐蚀原油蒸馏装置的反应机理。基于上述研究结果，归纳出在微量有机氯化物在原油蒸馏过程中的转移及转化规律，并预测馏分油中有机氯化物对原油后续加工的潜在危害。

由原油中有机氯化物衍生的氯化氢和氯化铵可以造成设备及管线的积垢、腐蚀和堵塞，严重威胁原油常减压蒸馏、石脑油重整预加氢和柴油加氢精制等许多装置的生产安全。因此，本项目对原油中有机氯化物的分布、鉴定、分子尺寸及其水解生成腐蚀性组分氯化氢的反应倾向进行了研究。在燕化原油基本物性测定的基础上，利用实沸点蒸馏将脱盐预处理后的原油切割成6个宽馏分油和22个窄馏分油。借助微库仑滴定仪和盐含量测定仪确定了原油中有机和无机氯化物在各馏分油中的分布趋势，在所有馏分油中，有机氯化物含量均显著高于无机氯化物。借助配备电子捕获检测器的气相色谱从300℃以下轻质馏分油中鉴定出属于氯代烷烃、氯代烯烃和氯代芳烃的17种有机氯化物，总结了低沸点和高沸点有机氯化物各自的分布特点，即低沸点氯化物几乎可共存于所有馏分油中，而具有电负性的高沸点物质仅存在于高沸程馏分油中，且其种类随着沸程的增加而增大。通过分子模拟确定了所鉴定出的有机氯化物的稳定分子结构及分子尺寸，17种氯化物的最小横截面直径均在0.62～0.92 nm范围内。基于炼厂原油蒸馏过程的操作条件，借助热力学分析评估了有机氯化物自发发生水解并生成氯化氢的可能性，阐明了原油蒸馏过程中可造成严重腐蚀问题的氯化氢生成机理，并预测了馏分油中有机氯化物对原油后续加工的潜在危害。因此，本项目的研究成果阐明了原油中有机氯化物在原油蒸馏过程中的转移及转化规律，对指导吸附、加氢等脱氯技术开发进而保障原油加工装置长周期、安全、稳定运行具有重要意义。