Novel Separation Processes using Solvents with a Critical Point of Miscibility

这项建议涉及最近开发的一种新的分离工艺，它可以为工艺设计者增加一个有价值的强大工具。它涉及多段逆流分离过程。这种方法的基本思想是基于使用具有临界点的溶剂对。通过在临界点附近操作并改变系统的温度，人们可以交替地创建两种溶剂形成均一溶液的区域，以及在其他区域中它们分成两个不同相的区域。这样的溶剂已经用于分离，但目前它们的使用距离相容的临界点很远。通过在每一段的临界点上操作，促进了混合区内的传质以及聚结过程。这允许低混合强度的设计，这对于由于杂质而有乳化或发泡倾向的分离将是有用的。它还适用于低扩散系数、高传质阻力的高分子化合物的分离。这允许一些新的设计选择，并将允许目前用现有的溶剂分离方法在经济上不可行的分离。基本概念已被证明，一个小的塔已经成功地运行。然而，为了以有效的方式应用这些过程，需要更好地理解所涉及的科学原理。这项建议的目的是为了提供理解，以及为未来的设计提供更好的科学基础。

This proposal deals with a novel separation process recently developed that could add a valuable and powerful tool to the process designer. It is concerned with multistage countercurrent separation processes. The basic idea underlying the approach is based on using pairs of solvents that have a critical point of miscibility. By operating close to the critical point and changing the temperature of the system, one can alternatively create regions where the two solvents form homogeneous solution and others in which they separate into two distinct phases. Such solvents are already used in separations, but at present they are used far from the critical point of miscibility. By operating across the critical point in each section, the mass transfer in the mixing zone as well as the coalescence process is facilitated. This allows design with low intensity of mixing, and this will be useful for separations in which there is a tendency to emulsification or foaming due to impurities. It is also suitable for separation of high molecular weight compound which have low diffusivities and therefore high mass transfer resistance. This allows some novel design options and will allow separations which are at present not economically feasible with existing solvent separation methods. The basic concept has been demonstrated and a small column has been successfully operated. However, in order to apply these processes in an efficient way, a better understanding of the scientific principles involved is required. The goal of this proposal is to provide understanding, as well as to provide a better scientific base for future design.