In carbon capture, utilization and storage (CCUS), a thorough understanding of thermophysical behaviour of the candidate fluid is an essential requirement for accurate design and optimised operation of the processes. In this communication, vapour liquid equilibrium data (VLE) of the binary mixtures of CO+CO2 are presented. A static-analytic method was used to obtain VLE data at six isotherms (253.15, 261.45, 273.00, 283.05, 293.05, 298.15) K and pressures up to 12 MPa. The standard uncertainties of the measured temperature and pressure were estimated to be 0.1 K, 0.005 MPa, respectively. Also, the standard uncertainty of the measured molar composition of each phase is found to be less than 1.1%. The measured experimental results are then compared with some predictive thermodynamic equations of state (EoS) (i.e. the Peng Robinson (PR-78) with classical or Wong-Sandler mixing rules, the GERG, and EoS-CG without an with a specific departure function) and available data in the literature. A sound agreement is observed between the results of this work and some of the VLE data published in the open literature. Furthermore, for all isotherms, the best agreement is observed between experimental results and predicted VLE data from the PR-EoS with the Wong-Sandler mixing rules and the EoS-CG with a specific departure function. However, a significant deviation is found between measured results and VLE data calculated using the GERG-EoS.

Glycols and their aqueous solutions are extensively utilized in the natural gas industry as hydrate inhibitors and desiccant agents. An increasing interest in new applications, such as subsea processing and carbon capture and storage (CCS) gas dehydration, requires evaluations for operations at high pressure. New measurements are presented for methane and a natural gas mixture (methane−ethane−propane− carbon dioxide) in tri(ethylene glycol) (TEG) and TEG aqueous solutions. Solubility measurements were carried out at pressures up to 40 MPa for temperatures T = (273.15 and 353.65) K. Water content data covers temperatures between (278.15 and 313.15) K at p = (6 and 12.5) MPa. In addition, water activities in such solutions are also reported. The experimental data were modeled with three different approaches: the simplified cubic-plus-association (sCPA), a Huron−Vidal Soave−Redlich−Kwong (SRK) equation coupled with the Non-Random Two-Liquid (NRTL) Gibbs energy (g ex ) expression (SRK/HV/NRTL), and the non-density-dependent approach to Peng− Robinson (PR/NDD). The SRK/HV/NRTL model was found wanting for correlating experimental methane solubility data, while the PR/NDD and sCPA were successful in describing the methane/TEG phase behavior but not TEG aqueous solutions. An alternative approach that includes a binary interaction parameter dependent on the liquid phase composition (xk ij ) gave fair to satisfactorily results, particularly in the case of sCPA. For the multicomponent system, sCPA-xk ij has yielded more consistent predictions than PR/NDD-xk ij , especially for total gas solubility. Overall, all the models have failed to give satisfactory results based only on binary parameters.

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