大庆减压渣油馏分油水界面张力的研究

OIL-WATER INTERFACIAL TENSION OF VACUUM RESIDUA FRACTIONS OF DAQING CRUDE OIL

采用超临界萃取分离技术 ,将大庆减压渣油按相对分子质量分割为 17个馏分 ,并对各馏分进行了化学组成分析和紫外光谱测定。在此基础上 ,采用吊环法对各馏分在不同条件 (馏分质量分数、油相组成、盐的种类及质量分数、水相 pH值 )下的油水界面张力进行了研究。结果表明 ,大庆减渣馏分相对分子质量逐渐增大 ,氢碳原子比逐渐下降 ,芳香共轭结构逐渐增多 ;随着馏分在油相中质量分数的增大 ,界面张力下降 ,且下降趋势相似 ,总体降幅不大 ;随着油相中庚烷的增多 ,界面张力降低。水相中CaCl2 使得油水界面张力上升 ,而NaCl或KCl对油水界面张力影响较小。水相 pH值在酸性范围内变化时 ,基本不影响油水界面张力 ,pH值在碱性范围内增大时 ,界面张力降低。

The vacuum residua of Daqing crude oil were separated into a series of 17 fractions according to the relative molecular weights of oil using the supercritical fluid extraction and fractional (SFEF) technology. The oil-water interfacial tension of each fraction was analyzed under different conditions. It is shown that the value of molecular weight and the content of aromatic component increased, and the H/C atomic ratio decreased in the order of series. The effect of some factors including fraction concentrations in oil phase, ratio of oil component, salts dissolved in water phase and pH value on the interfacial tension were studied with the lifting ring method. It is concluded that the interfacial tension decreases when the mass ratio of fractions in oil phase increases. The decreasing tendencies of all fractions are almost same although the reduction degree is not too big. As the heptane in oil phase increases, the interfacial tension decreases. Adding NaCl or KCl in water phase has a little effect on the interfacial tension, while addition of CaCl\-2 can result in increase of the interfacial tension. The interfacial tension is almost stable as pH value changes in the acid range, while it will decrease rapidly as pH value increases in the range of alkalinity.