Evaluating cubic equations of state for calculation of vapor–liquid equilibrium of CO 2 and CO 2-mixtures for CO 2 capture and storage processes

Abstract

Proper solution of vapor liquid equilibrium (VLE) is essential to the design and operation of CO 2 capture and storage system (CCS). According to the requirements of engineering applications, cubic equations of state (EOS) are preferable to predict VLE properties. This paper evaluates the reliabilities of five cubic EOSs, including PR, PT, RK, SRK and 3P1T for predicting VLE of CO 2 and binary CO 2-mixtures containing CH 4, H 2S, SO 2, Ar, N 2 or O 2, based on the comparisons with the collected experimental data. Results show that SRK is superior in the calculations about the saturated pressure of pure CO 2; while for the VLE properties of binary CO 2-mixtures, PR, PT and SRK are generally superior to RK and 3P1T. The impacts of binary interaction parameter k ij were also analyzed. k ij has very clear effects on the calculating accuracy of an EOS in the property calculations of CO 2-mixtures. In order to improve the calculation accuracy, the binary interaction parameter was calibrated for all of the studied EOSs regarding every binary CO 2-mixture.