The Curious Behavior of Homogeneous Azeotropic Distillation-Implications for Entrainer Selection
The Curious Behavior of Homogeneous Azeotropic Distillation-Implications for Entrainer Selection
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DOI：
10.1002/aic.690380902
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发表时间：
1992-09
期刊：
影响因子：
3.7
通讯作者：
L. Laroche;N. Bekiaris;H. W. Andersen;M. Morari
中科院分区：
文献类型：
--
作者：
L. Laroche;N. Bekiaris;H. W. Andersen;M. Morari
我们研究了最简单的均相共沸蒸馏序列的工业相关性，其中添加一个共沸剂的二元共沸物回收共沸组分作为纯产品。尽管其明显的简单性，这种蒸馏塔可以表现出在非共沸蒸馏中没有观察到的不寻常的行为：对于某些混合物，分离作为回流的函数经历最大值。在无限回流下，没有实现分离。在某些情况下，用更多的塔板实现相同的规格需要更大的回流。有时，唯一可行的分离产生作为纯馏出物的中间组分，而底部产物包含轻组分和重组分。有时，唯一可行的分离产生作为纯底部产物的中间组分，而馏出物包含轻组分和重组分。虽然这些不寻常的功能可以被视为好奇心，他们是必不可少的适当的选择和设计。对于最低沸点共沸物，现有的和相互矛盾的共沸物选择规则指出，应当使用在共沸组分之间不引入蒸馏边界的组分（Doherty和卡尔达罗拉，1985），以及不引入额外的共沸物的低或高沸点组分或引入新的最低沸点共沸物的组分（Stichlmair等人，1989年）。通过利用上述奇怪的特征，以及我们涉及400多种混合物的经验，我们已经能够分析这些标准背后的假设，显示这些假设何时被打破，从而了解标准的局限性。
We examine the simplest homogeneous azeotropic distillation sequence of industrial relevance, where an entrainer is added to a binary azeotrope to recover both azeotropic constituents as pure products. Despite its apparent simplicity, such distillation columns can exhibit an unusual behavior not observed in zeotropic distillation: For some mixtures, separation as a function of reflux goes through a maximum. At infinite reflux, no separation is achieved. In some cases, achieving the same specifications with a larger number of trays requires a larger reflux. Sometimes the only feasible separation yields the intermediate component as a pure distillate, while the bottom product contains the light and heavy components. Sometimes the only feasible separation yields the intermediate component as a pure bottom product while the distillate contains the light and heavy components. While these unusual features can be regarded as curiosities, they are essential for proper entrainer selection and design. For a minimum boiling azeotrope, the existing and conflicting entrainer selection rules state that one should use a component that introduces no distillation boundary between the azeotropic constituents (Doherty and Caldarola, 1985), and either a low or high boiling component that introduces no additional azeotrope or a component which introduces new minimum boiling azeotropes (Stichlmair et al., 1989). By taking advantage of the curious aforementioned features, as well as our experience involving more than 400 mixtures, we have been able to analyze the assumptions behind these criteria, show when those assumptions break down, and therefore understand the limitations of the criteria.