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 (gex) 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 (xkij) gave fair to satisfactorily results, particularly in the case of sCPA. For the multicomponent system, sCPA-xkij has yielded more consistent predictions than PR/NDD-xkij, especially for total gas solubility. Overall, all the models have failed to give satisfactory results based only on binary parameters.
ASJC Scopus subject areas
- Chemical Engineering(all)