DENSITY CALCULATIONS OF AQUEOUS AMINE SOLUTIONS USING AN EXCESS GIBBS BASED MODEL

Abstract Accurate representation of the physical properties of a solvent is essential for design and simulation of processes. Density and viscosity, for instance, have an important role in modelling and designing absorption and desorption towers. In the present work, a model to accurately calculate the density of aqueous amine solutions used in CO2 capture was developed as a function of temperature and composition. The model is based on excess Gibbs energy functions, and in this work the functional form of the non-random two-liquid (NRTL) model was used. The model is able to accurately represent the density of the tested systems with deviations below 0.2% for most cases. The pure component density was calculated using the modified Rackett equation with the parameter ZRA as a function of the temperature and pressure of the system. The calculated deviation (AARD) for pure component density was below 0.09%.

摘要 精准表征溶剂的物理性质对于工艺设计与过程模拟至关重要。以密度与黏度为例，二者在吸收塔及解吸塔的建模与设计中发挥着重要作用。本研究开发了一款可精准计算二氧化碳（CO₂）捕集过程中所用胺水溶液密度的模型，该模型以温度与组分为自变量。模型基于超额吉布斯自由能（excess Gibbs energy）函数构建，本研究采用了非随机双液体（non-random two-liquid, NRTL）模型的函数形式。在多数测试体系中，该模型可精准复现被测体系的密度，绝大多数情况下偏差低于0.2%。纯组分密度通过修正拉凯特方程（modified Rackett equation）计算，其中参数ZRA以体系的温度和压力为函数。纯组分密度的计算平均绝对相对偏差（Average Absolute Relative Deviation, AARD）低于0.09%。