【作者】 张蕾蕾；

【导师】 王宗贤；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2011， 硕士

【摘要】 渣油在储存、运输、加工过程中均会受到胶体稳定性的影响。如炼厂在渣油延迟焦化加工过程中,可能会出现原料混合罐中沉积、换热器沉积结焦、加热炉管结焦和产物分布变差等问题;一些渣油减粘之后处理不当在运输过程中会分相,沉积,装卸难度都很大,给工业操作带来麻烦。这些问题想要得到有效地解决,就需要选择合适的胶体稳定性评价方法。本文在前人对于渣油原油稳定性研究的基础之上,首先研究了四种稳定性评价方法-质量分数电导率法、分光光度法、HRS值法、EP值法对实验选用渣油的适用性。结果表明,质量分数电导率法是一种简单快捷的、结果直观的实验方法,对于渣油稳定性评价结果准确,且应用范围广,而且实验结果符合渣油本身性质,可以定量的给出实验结果;HRS值法结果直观,可以定性也可以定量,但是对于油品的选择性较高;紫外分光光度法需要采用多点法数据步骤较为复杂,结果准确度较高,低稀释下测得的沥青质起始点与浓度呈直线,高稀释条件下得到的曲线呈指数型;EP值法既可以定性定量的说明渣油的稳定性,EP0/EPmin还可以用于预测该油品能否与其它油品混合而不造成稳定性问题。此外,通过渣油结构的分析,实验考察了渣油结构性质与稳定性的关系,认为渣油各组分的含量、结构都对渣油胶体稳定性有影响,具有较低的H/C比、且芳碳率和芳环数、偶极距等较大的沥青质较容易从渣油中分离出来,从而破坏沥青质稳定结构;沥青质的沉积不但与沥青质的含量有关,还与体系对其分散状况有关。其次,采用质量分数电导率方法研究了搀兑体系渣油稳定性的变化情况。实验结果表明可知,两种稳定性不好的油品搀兑稳定性会变差,掺入与渣油相容性较好的馏分油可增强渣油稳定性。热反应过程中,渣油稳定性变差,但是加入了适当的馏分油,会延缓稳定性变差,从而延缓生焦诱导期;馏分油搀兑的越多稳定性改善的越多。生焦诱导期不光是胶体稳定性决定的,还与其他因素有关,如残炭,等。再次,由于添加抑制剂是增强体系稳定性的重要方法,实验还采用相对准确、快捷的质量分数电导率法评价了几种沥青质分散剂的优劣及其作用原理。实验结果说明,与渣油配伍性好的试剂对沥青质抑制作用更强,配伍性不好的可能会加速沥青质从渣油体系中沉积出来。更多还原

【Abstract】 Colloidal stability of petroleum influences the reservoir, transporting and process of crude oils. During delayed coking process of residues, colloidal instability problem might occur, and cause fouling in the storage tanks and heat exchanger, coke formation on the wall of the furnace tubes and nozzles, or the undesirable product distribution which seriously affected the normal operation of oil refinery. Some residues might phase split during transportation, and lead to the difficulty of loading and unloading of the residues. To work out these problems, suitable methods for testing colloidal stability must be selected or set up.Firstly, four methods were characterized for testing colloidal stability. Results show that, mass fraction conductivity method is a simple, swift method. It can give an accurate result that fitted the properties of the residues in where it was used and can be used in a wide range. This method tells the differences of residues but do not tell whether the oil is stable or not, researches need to compare oil samples to get the result they want. HRS value method shows the result in an intuitive way, the result can be given in both qualitative and quantitative ways, however it can not be used in a wide range. Ultraviolet spectrophotometric method needs multi-steps to carry out one measurement. It might be complex, but the results with this method are accurate. In low dilution system asphaltene precipitation starting points have a linear relationship with their concentrations in toluene; while in high dilution system the relation is exponent. EP value method can not only tell the results in both qualitative and quantitative ways, but also foretells residues compatibility when they are blended with other oils through a parameter EPo/EPmin. Besides, the relationships of colloidal stability with residues components and their properties are examined. It is shown that the composition and the properties determine the stability of the residues. Asphaltenes with low H/C ratio and more polarity, higher aromaticity and condensation degree easily deposits from residues and ruined the stability of its colloidal system. Deposition of asphaltenes depends on asphaltene contents and also their dispersion conditions.Secondly, the stabilities of residues colloidal system were studies when they were mixed with other oils. Results show that when two oils both with low stabilities were blended their mixture oil has lower colloidal stability. And when residues with similar compatibility were mixed together, the colloidal stability of the mixture can be improved. During thermal reaction, residues colloidal stability became worse, but the situation can be delayed by being added suitable fraction oils, and the more, the better. Colloidal stability is not the only cause influencing the induction period of coke formation, other factors like carbon residue also play important role.Thirdly, addition of asphaltene deposition inhibitor is an effective way of improving residues stability. The determination of the colloidal stability of residues by mass fraction conductivity method was conducted in order to appraise the performance of several asphaltene deposition inhibitors. Results show that inhibitors with good compatibility with residues can improve colloidal stability of residue system, otherwise, it can accelerate asphaltene depositing rate from residues.更多还原