ENRTL parameter fitting procedure for blended amine systems: MDEA-PZ case study

Abstract

Although chemical absorption is a well-known and established process, design and scale up of equipment are still a challenge. An accurate thermodynamic model will lead to good representation of the system behavior and therefore a more precise design of equipment. The eNRTL model is suitable for amine based processes due to its ability to handle electrolyte systems. However, this model requires that a large number of parameters are fitted against experimental data, usually partial and total pressures. In this work, the blended MDEA (N-methyldiethanolamine) and PZ (Piperazine) system is presented as an example case for showing a new procedure to estimate the eNRTL parameters. The largest system studied is the MDEA/PZ/CO2/H2O, and the subsystems are formed by suppressing one or more components from the initial mixture, for instance: MDEA/H2O, PZ/CO2/H2O. The parameter fitting procedure consists of estimating the smaller subsystems' parameters and using them further on to estimate the larger systems. Results show that this procedure gives accurate predictions for all the systems. Moreover, it's possible from the complete model to estimate one of these subsystems without losing accuracy.