Measurement and Modeling of CO2 Frost Points in the CO2-Methane Systems

Technology is being developed to separate carbon dioxide (CO2) from natural gas by frosting CO2 out from the mixture. Vapor-solid phase equilibrium data in the CO2-methane systems are important in developing such processes. In this work, new experimental data are reported for the frost points in the CO2 methane systems for a wide range of CO2 range concentration (i.e., CO2 mole fraction 0.108 to 0.542). The Soave-Redlich-Kwong (SRK) equation of state (EoS) is employed to calculate the fugacity of the fluid phase. The CO2 solid-forming conditions are modeled by a solid fugacity model based on the sublimation pressure of pure CO2. The thermodynamic model was used to predict the CO2 frost points in the presence of methane. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.