Predictive Thermodynamic Modeling of Poorly Specified Mixtures and Applications in Conceptual Fluid Separation Process Design

Abstract

In many chemical engineering processes, mixtures occur whose composition is not well-known. Simulations of processes with such poorly specified mixtures are basically infeasible, as thermodynamic models require knowledge of the speciation. As a workaround, pseudo-components can be introduced which are generally defined using ad-hoc assumptions. In a previous series of works, we have developed and tested a method for quantifying the group composition of poorly specified mixtures based on simple NMR experiments without having to solve the much more complicated task of quantifying all species. This method has been extended recently to a rational method for defining pseudo-components in poorly specified mixtures. In the present work, this method is combined with several thermodynamic group-contribution methods. The resulting thermodynamic models were applied to various poorly specified mixtures and used for solving two typical tasks from conceptual fluid separation process design: a) solvent screening for liquid−liquid extraction processes and b) the simulation of open evaporation processes. The results show excellent agreement with those obtained using the complete information on the speciation, which was known for the studied test mixtures but disregarded in applying the new approach.

HybridGamma: A thermodynamically consistent framework for hybrid modelling of activity coefficients

“…However, analyzing the mixture using spectroscopic techniques and involving group contribution methods to estimate the mixture excess properties is still possible. In this regard, many works have been published [19][20][21][22][23][24]. Furthermore, some frameworks have been developed to estimate the propagation of the uncertainty from the physical parameters (e.g., activity coefficients and excess properties) to the flowsheet simulation and optimization [25,26].…”

Virtual Issue: A Multiscale View on Molecular and Process Design

“…Thermodynamic modeling was discussed by Specht et al . for the case of poorly specified mixtures, while Yousefi Seyf and Asgari focused on parametrizing the PC-SAFT equation of state for the solvents used in the pharmaceutical industry.…”