管道蜡沉积模型中扩散系数的研究

Research on the Diffusion Coefficient in the Model of Pipeline Wax deposition

分子扩散是管道蜡沉积的主要驱动力,蜡分子的径向扩散质量流(J=D?(dC/dr))决定了蜡沉积层增长速率,其中关键参数为蜡分子在原油中的扩散系数D。原油为多组分复杂混合物,扩散过程复杂,不利于定量研究。从简单的二元烷烃体系入手,研发了Taylor分散法测试装置,并总结了国内外学者的理论和实验研究,针对n-C18+n-C7体系进行比较分析,为深入研究多元蜡分子扩散现象提供了基础。

Molecule diffusion is the major driving force for wax deposition. The mass flux of wax molecules（J=D·（dC/dr））determines the wax deposit increasing rate. Consequently, the amount of diffusion coefficient playsa significant role in prediction of wax despite increasing rate. However, the crude is a complex mixture, increasing the difficulties in quantitatively investigation of mass transfer process.In this paper,the simple two-component hydrocarbon mixture of （n-C18＋n-C7） was used to measure the diffusion coefficient ofn-C18inn-C7. Using the HPLC unit, an apparatus was developed according to Taylor Diffusion principle. This apparatuswas used to measureDof n-C18inn-C7. The predicted diffusion coefficients were compared with the measured values.This workcanprovidea foundation for further research on diffusion process in complex liquid mixtures.