A Quantitative Study of Drop Coalescence in Stirred Dispersion

本项目研究了搅拌液-液分散体中影响液滴聚结的几种因素，这些因素可有效地用于控制液滴数量。本文从实验和理论两方面研究了液滴表面电荷对聚结现象的影响。通过添加电解质和表面活性剂以及改变介质的pH值，可以实现对表面电荷效应的操纵。研究了湍流强度对液滴聚结的影响，并通过向色散中输入能量来控制液滴大小。由于大多数工业液-液接触操作涉及高分散相馏分，因此该项目通过利用自相似行为和结垢特性来研究密集分散。在这项工作中提出的方法是独特的，因为信息将在单个液滴水平上获得，因此除了依赖于其他物理参数外，还可以获得作为液滴大小函数的聚结率。在这项工作中提出的研究效果要么是完全未知的，要么充其量是模棱两可的，因为研究结果对液滴大小分布不敏感。为了控制分散相系统，以便接触操作能够在转化率和选择性方面最佳地进行，了解上述影响是很重要的。

This project is an investigation of several effects on drop coalescence in stirred liquid-liquid dispersions which may be used effectively to control drop populations. Thus the effect of surface charge on droplets and its manipulation by various means on coalescence phenomena is investigated experimentally and theoretically. The manipulation of surface charge effects are accomplished by addition of electrolytes and surfactants, and by varying the pH of the medium. The effect of turbulence intensity on drop coalescence is investigated as a method to control drop sizes by energy input to the dispersion. Since most industrial liquid-liquid contacting operations involve high dispersed phase fractions, the project investigates dense dispersions by exploiting self-similar behavior and scaling properties. The approach presented in this work is unique in that information will be obtained at the individual droplet level so that coalescence rates are obtained as functions of drop sizes in addition to their dependence on other physical parameters. The effects proposed for study in this work are either completely unknown or are at best ambiguous as obtained from studies insensitive to drop size distributions. It is important to understand the foregoing effects in order to control dispersed phase systems so that contacting operations can be performed optimally with respect to conversion and selectivity.