Calculation of solid-vapor equilibria for cryogenic carbon capture
Giorgia De Guido, Laura A. Pellegrini
Abstract
• Novel technologies have been developed for cryogenic separation of CO 2 . • Cryogenic CO 2 separation from flue gas requires solving solid-vapor equilibria. • The classical thermodynamic approach is applied to solid-vapor equilibria. • Operating conditions can be determined for achieving a desired CO 2 capture rate. This work deals with the thermodynamic modeling of phase equilibria calculations in the presence of solid carbon dioxide for application to CO 2 capture from flue gas by desublimation. The proposed solid-vapor equilibria calculation method is based on the classical approach, namely on the equality of components’ fugacities in the different phases and on the use of an expression for the fugacity of the freezing component in the solid phase. The results obtained with the proposed method are validated for the system CO 2- N 2 by comparison with literature experimental data and for the system CO 2- N 2- O 2 by comparison with the results reported in the literature and those obtained using another tool that makes use of Gibbs free energy minimization. The good agreement obtained in both cases suggests that the proposed approach can be used for determining suitable operating conditions for processes aimed at separating CO 2 out of flue gas by freezing it out.