Session: 11-11-01 Advances in Carbon Capture Utilization and Storage

Paper Number: 80010

80010 - Phase Behavior Modeling for Carbon Dioxide/Brine Mixtures Using PR EOS and Huron-Vidal Mixing Rule 

Accurately predicting CO₂ solubility in saline aquifers is very important for CO₂ capture and storage. A reliable and accurate thermodynamic model is needed to accurately predict the phase behavior of the CO₂+brine systems over a wide range of temperature, pressure, and molality. This study aims at developing a cubic-equation-of-state-based thermodynamic model that can accurately describe the phase behavior of the CO₂+brine systems. Peng-Robinson equation of state (PR EOS) (Peng & Robinson, 1976) and the Huron-Vidal (HV) mixing rule (Huron and Vidal, 1979) are utilized to model the phase equilibria of CO₂+brine systems containing salt species including NaCl, KCl, CaCl₂, and MgCl₂. Binary interaction parameters as functions of temperature and salt molality are established for specific CO₂+single-salt+H₂O systems. The model is extended to account for the effects of different salt species on CO₂ solubility in aqueous phase solutions, which can cover the typical geological conditions (273-550K, 0-800 bar, 0-6 mol/kg). We employ the PR EOS together with the proposed BIP strategy in the HV mixing rule to reproduce the mutual solubility of CO₂ and H₂O in vapor-liquid equilibria (VLE). The collected experimental data are used to determine the optimal BIP model. The validation of the model calculations against the available experimental data indicates that the average absolute percentage error (%AAD) in reproducing the CO₂ concentration in the mixed-salt brine is 12.63%. Compared to the calculation results provided by the state-of-the-art models in the literature (Søreide & Whitson, 1992; Sun et al., 2021), the PR EOS together with the proposed BIP strategies in the HV mixing rule can more accurately predict the VLE of CO₂+brine systems over large ranges of temperature, pressure, and molality.

Presenting Author: Ziting Sun University of Alberta

Authors:

Ziting Sun University of Alberta
Huazhou Li University of Alberta