Weak Electrolyte Vapor-Liquid Equilibria

这项早期的工作主要集中在汽相上，因此成功地表征了给定整体液相组成的汽相行为。在这个项目中，工作重点将放在液体上。具体地说，将审查对现有模型的几项拟议修改，以便成功地表征液体中单个物种的浓度。最后，将进行一项实验计划，利用该计划，将在现场测量两相的总压力、温度、密度和电导率。这些结果与理论模型一起，将被用于计算相组成。创新：拟议的工作将导致两项科学创新。首先，它将继续发展状态方程在弱电解质体系中的应用。状态方程的发展将导致一个比目前用来表示弱电解质行为的模型更简单的模型。所提出的方法将具有许多优点，这些优点使状态方程在表示非电解质汽液平衡时变得如此流行。第二个创新是将开发一种实验技术，它将消除从平衡池中取出和分析样品的需要。以目前的技术，这是最困难的一步，因此它的消除确实将是用于研究这些系统的方法的重大发展。这项工作之所以适用于如此多的领域，是因为用于CO2-NH3-H2O和H2S-NH3-H2O体系的技术可以很容易地扩展到氨被胺、乙二醇或醇取代的体系。因此，由于胺处理脱除天然气中H_2S的重要性，引起了工业上的极大兴趣。在这一点上，与弱电解质VLE相关的问题还没有得到令人满意的解决。所提出的技术将实验过程中的新方法与以可能解决问题的方式对行为建模的新方法结合起来。

Research Summary: An equation of state model which successfully correlates vapor liquid equilibria behavior of weak electrolyte systems containing ammonia, hydrogen sulfide, and carbon dioxide has recently been developed by the principal investigators. This earlier work was focused primarily on the vapor phase, so that the vapor phase behavior for a given overall liquid phase composition was successfully characterized. In this project, work will focus on the liquid phase. Specifically, several proposed modifications to the existing model will be examined so that concentrations of individual species in the liquid phase will be successfully characterized. In addition, the feasibility of replacing the perturbed hard chain equation, which is presently in the model, with a cubic equation of state, will be examined. Finally, an experimental program will be undertaken whereby total pressure, temperature, and the density and conductivity of both phases will be measured in situ. These results, along with the theoretical model, will then be used to calculate phase compositions. The program will eliminate the two features which have given traditional methods so much trouble--overly complex theoretical models and removing and analyzing samples from equilibrium cells. Innovation: The proposed work will lead to two scientific innovations. First, it will continue to develop the application of equations of state to weak electrolyte systems. The equation of state development will lead to a model which will be simpler than those models currently used to represent weak electrolyte behavior. The proposed methods will possess the many advantages which have made equations of state so popular for representing non-electrolyte vapor liquid equilibria. The second innovation is that an experimental technique will be developed which will eliminate the need to remove and analyze samples from the equilibrium cell. With current techniques, this is the most difficult step, so its elimination will indeed be a major development in the methods used to study these systems. Significance: The proposed research will have considerable practical impact in the area of sour water processing, water purification, natural gas processing, and heavy oil refining. The reason this work is applicable in so many areas is that techniques for the CO2-NH3-H2O and H2S-NH3-H2O systems can be easily extended to systems in which the ammonia is replaced by amines, glycols, or alcohols. Thus, much industrial interest results because of the importance of H2S removal from natural gas by amine treating. At this point, the problems associated with weak electrolyte VLE have not been solved satisfactorily. The proposed techniques couple new approaches in the experimental procedure with new approaches to modelling the behavior in a manner that may solve the problem.