化工学报 ›› 2014, Vol. 65 ›› Issue (2): 605-612.DOI: 10.3969/j.issn.0438-1157.2014.02.034

• 分离工程 • 上一篇    下一篇

采用泰勒分散法测量蜡分子扩散系数

陈普敏1,2, 韩善鹏1, 李鸿英1, 张劲军1   

  1. 1 中国石油大学(北京)油气管道输送安全国家工程实验室/城市油气输配技术北京市重点实验室, 北京 102249;
    2 新疆石油勘察设计研究院(有限公司), 新疆 克拉玛依 834000
  • 收稿日期:2013-03-27 修回日期:2013-08-27 出版日期:2014-02-05 发布日期:2014-02-05
  • 通讯作者: 韩善鹏
  • 基金资助:

    国家自然科学基金项目(51134006,51204194);中国石油大学(北京)基金项目(KYJJ2012-04-06)。

Measurement of diffusion coefficients of paraffin molecules using Taylor dispersion method

CHEN Pumin1,2, HAN Shanpeng1, LI Hongying1, ZHANG Jinjun1   

  1. 1 National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum(Beijing), Beijing 102249, China;
    2 Xinjiang Petroleum Survey and Design Institute(Co., Ltd), Karamay 834000, Xinjiang, China
  • Received:2013-03-27 Revised:2013-08-27 Online:2014-02-05 Published:2014-02-05
  • Supported by:

    supported by the National Natural Science Foundation of China(51134006,51204194).

摘要: 蜡分子扩散系数是蜡沉积预测模型中非常重要的物性参数。为测量蜡分子(高碳数正构烷烃)在液相体系中的分子扩散系数,建立了基于泰勒分散法的扩散系数测量装置,并对装置操作注意事项进行了详细探讨。采用该装置测量了丙酮水溶液、n-C6+n-C7溶液以及甲醇水溶液中溶质在溶剂中的分子扩散系数,以文献值对测量值进行校验,验证了装置的可靠性。分别以n-C18n-C20n-C22n-C24n-C26为溶质,以n-C7为溶剂,在不同温度、浓度下测量蜡分子在液相体系中的分子扩散系数,并将实验测量值与Hayduck-Minhas关系式计算值进行比较。结果表明:蜡分子扩散系数随温度升高而线性增大,随溶液中蜡分子摩尔分数的增大而以指数形式减小;在相同条件下,高碳数正构烷烃的分子扩散系数低于低碳数正构烷烃的分子扩散系数。采用Hayduck-Minhas关系式的计算结果比实验测量结果平均小50%,应用于蜡沉积预测时,将低估蜡分子扩散质量流。

关键词: 扩散, 层流, 传质, 泰勒分散法, 蜡沉积

Abstract: The diffusion coefficient of paraffin molecules is of importance in the wax deposition prediction models. In this work, an instrument based on the principle of Taylor dispersion method was built in order to measure the diffusion coefficient of paraffin molecules in the model crude oil. The newly developed apparatus was carefully calibrated and adequate operating conditions were summarized. Measured with this apparatus, the diffusion coefficients (DAB) of methanol in water, acetone in water, and hexane in heptane agree with those in literature, with an absolute deviation 1.13%. Using heptane as the solvent, six binary solutions were prepared with n-C18, n-C20, n-C22, n-C24 and n-C26 as solute. DAB of a solute in a solvent was measured at the temperature from 30℃ to 50℃. It is found that the diffusion coefficient of paraffin molecules increases linearly with temperature. As solute concentration increases, diffusion coefficients decrease exponentially. In the same solvent, paraffin molecules with longer chain present higher diffusion coefficient. The measured DAB is compared to that obtained by empirical equation. The calculated DAB by Hayduck-Minhas correlation are 50% lower than measured values. Obviously, the wax deposition prediction models employing Hayduck-Minhas correlation will underestimate the mass flux of wax molecules from the main flow to the pipe wall.

Key words: diffusion, laminar flow, mass transfer, Taylor dispersion method, wax deposition

中图分类号: