Representing Vapor-Liquid Equilibrium for an Aqueous MEA-CO2 System Using the Electrolyte Nonrandom-Two-Liquid Model

Following the work of Austgen et al., the electrolyte nonrandom-two-liquid (NRTL) model was applied in a thermodynamically consistent manner to represent the vapor-liquid equilibrium (VLE) of the aqueous monoethanolamine (MEA)-CO2 system with rigorous chemical equilibrium consideration. Special attention was given to the accurate VLE description of the system at both absorbing and stripping conditions relevant to most aqueous MEA absorption/stripping processes for CO2 removal. The influence from chemical equilibrium constants, Henry’s constant, experimental data, and data regression on the representation of the VLE of the system was discussed in detail. The equilibrium constant of the carbamate reversion reaction as well as important interaction parameters of the electrolyte NRTL model were carefully fitted to experimental data. A good agreement between the calculated values and the experimental data was achieved. Moreover, the model with newly fitted parameters was successfully applied to simulate three industrial cases for CO2 removal using a rate-based approach. The results from this work were compared with those using the model by Austgen et al.