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Intensification of liquid-liquid contacting processes.

机译：液-液接触过程的加剧。

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摘要

In order to improve mass transfer rate and efficiently employ energy in liquid-liquid contacting processes, especially in biodiesel production through transesterification, two process intensification technologies were addressed based on two different energy sources and were investigated in this dissertation. They include electrostatic liquid spraying based on electric field and a two-disc spinning disc reactor based on high gravity field.;Interfacial turbulence plays an important role in electrically enhanced mass transfer. One specific aspect of this work was to investigate interfacial turbulence which can occur at the interface between two phases because of interfacial tension gradients resulting from the change of charge density across droplet surface. Firstly, a Schlieren optical technique was developed and the experimental setup was built for the visualization of electrically induced interfacial phenomena in the ethanol-water-1-decanol system. Two Schlieren cells were designed and fabricated, and were successfully used for the interrogation of interfacial disturbances in pendant droplets and at plane interfaces. The mechanism of interfacial turbulence was further understood by study of these Schlieren images. Additionally, interfacial mass transfer in the ethanol-water-1-decanol system was investigated in the presence of electric fields and mass transfer coefficients were measured from the pendant droplets. Initial results show that a time-dependent nature was presented and mass transfer was intensified by the application of electric fields.;As an alternative biofuel, biodiesel is produced through transesterification of vegetable oils, fat and algae lipids and alcohol with the help of acid or base. Transesterification is a liquid-liquid two phase reaction, whose rate is limited by mass transfer between oil and alcohol due to their immiscibility. This work firstly applied electrostatic liquid-liquid contactors to improve biodiesel synthesis. The reaction rate of transesterification of canola oil with sodium methoxide was investigated in the plane interface contactor. A fourfold enhancement was observed at an applied voltage of 10kV DC. A compact electrostatic spraying reactor based on simple tubular geometry with horizontal injection of an electrostatic spray of sodium methoxide was developed to achieve continuous biodiesel production. Preliminary data demonstrate it is a promising technology.;A novel two-disc spinning disc reactor was developed as another alternative for biodiesel synthesis. It comprises two flat discs, located coaxially and parallel to each other with a very small gap between the discs. A grooved rotating disc was integrated to increase residence time allowing relatively slow transesterification reaction to be as complete as possible. The reaction performance was investigated widely. The conversion achieved in the reactor was significantly influenced by the size of inter-disc gap, the rotational speed, the canola oil phase flowrate, the surface topography of the rotating disc, and the reaction temperature. The experimental conditions were optimized. Finally, the new reactor was also compared with the stirred tank reactor according to the data of conversion rates and droplet size distribution of the emulsions.
机译：为了提高传质速率并有效地在液-液接触过程中利用能量，特别是在通过酯交换反应生产生物柴油的过程中，针对两种不同的能源，提出了两种工艺强化技术，并进行了研究。其中包括基于电场的静电液体喷涂和基于高重力场的两盘式旋转盘式反应器。界面湍流在电增强质量传递中起着重要作用。这项工作的一个特定方面是研究界面湍流，该界面湍流可能由于液滴表面电荷密度的变化而引起的界面张力梯度而在两相之间的界面处发生。首先，开发了一种Schlieren光学技术，并建立了用于可视化乙醇-水-1-癸醇系统中电界面现象的实验装置。设计并制造了两个Schlieren单元，并成功地用于悬垂液滴和平面界面的界面扰动的询问。通过研究这些Schlieren图像，可以进一步了解界面湍流的机理。另外，在电场存在下研究了乙醇-水-1-癸醇系统中的界面传质，并从悬滴测量了传质系数。初步结果表明存在时间依赖性，并且通过施加电场增强了传质。作为替代性生物燃料，生物柴油是通过植物油，脂肪和藻类脂质以及酒精在酸或酸的帮助下进行酯交换反应而生产的基础。酯交换反应是液-液两相反应，由于不溶性，其速率受油和醇之间的传质限制。这项工作首先应用静电液-液接触器来改善生物柴油的合成。在平面界面接触器中研究了菜籽油与甲醇钠的酯交换反应速率。在施加的10kV DC电压下观察到四倍的增强。开发了一种基于简单管状几何结构的紧凑型静电喷涂反应器，其中水平注入了甲醇钠的静电喷雾，以实现连续的生物柴油生产。初步数据表明，它是一种有前途的技术。开发了一种新型的两盘式旋转盘式反应器，作为生物柴油合成的另一种选择。它包括两个同轴且相互平行的扁平圆盘，圆盘之间的间隙很小。集成了带凹槽的旋转盘以增加停留时间，从而使相对缓慢的酯交换反应尽可能完整。反应性能得到了广泛的研究。盘间间隙的大小，转速，低芥酸菜子油相的流速，转盘的表面形貌和反应温度对反应器中获得的转化率有显着影响。优化了实验条件。最后，根据乳液的转化率和液滴尺寸分布的数据，还将新反应器与搅拌釜反应器进行了比较。

著录项

  • 作者

    Qiu, Zheyan.;

  • 作者单位

    University of Kansas.;

  • 授予单位 University of Kansas.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 198 p.
  • 总页数 198
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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