NH3 – CO2 – NaCl – H2O system activity coefficients simplified prediction model

Abstract

The study of CO₂ capture systems from flue gases and simultaneous reduction of the Na+ content of rejection brine from dual-purpose plants for water and energy generation is of growing interest. This work consists of obtaining simple correlations for the estimation of NH₃ – CO₂ – NaCl – H₂O system activity coefficients. Firstly, considering temperatures and concentrations representative of these processes, the vapor – liquid equilibrium is simulated using the eNRTL model in Aspen Plus software. Then, to obtain a simple model, the adjustment of the activity coefficient values to a second-degree multivariable polynomial function with parameters to be determined by implementing an optimization problem in GAMS software is proposed. The correlations obtained for the 10 species in solution present high determination coefficients (> 0.99) which is acceptable for its application.