Calculation Models for Vapor-liquid Phase Equilibrium in Mixture Systems of CO2 Containing Impurities
The accurate characterization of the phase equilibrium for CO2 systems containing impurities is a crucial step in CCUS applications.In order to discuss the optimal thermodynamic model for phase equilibrium descriptions of the systems,this paper conducts flash calculations based on the vapor-liquid equilibrium data of CO2/N2,CO2/O2,and CO2/H2O using equations of state(PR、SRK、BWRS、CPA、GERG-2008)and activity coefficient models(NRTL、UNIQUAC).The results indicate that the CPA equation has the highest accuracy for the calculation of vapor-liquid phase equilibrium of the binary CO2 mixtures containing impurities,with the average deviation from the experimental data of 4.75%.The phase envelope of CO2/N2、CO2/N2/O2,and CO2/N2/O2/H2O are then predicted using CPA,and the average deviations for its calculated bubble and dew point pressures from the NIST results are lower than 3.5%.These two calculations imply that the CPA equation can be a simple and accurate method to calculate vapor-liquid phase equilibrium in mixture systems of CO2 containing impurities.
CO2 containing impuritiesPhase equilibriumActivity coefficient modelsEquations of state
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