(365e) Water Content of Natural Gas Systems in Equilibrium with an Aqueous or a Hydrate Phase – Experimental Measurements and Molecular Modeling

Accurate determination of hydrate formation conditions and water content of natural gas systems is critical for cryogenic processes used in the production of natural gas liquids (NGL), liquefied natural gas (LNG) processing and carbon dioxide (CO₂) capture. Water content of three sweet and sour natural gas mixtures was measured using a Panametrics moisture analyzer at low temperatures and pressures up to 40 MPa. A molecular model based on the statistical associating fluid theory (SAFT) was developed to predict water content of pure alkanes, carbon dioxide (CO₂), hydrogen sulfide (H₂S), nitrous oxide (N₂O), nitrogen (N₂) and argon (Ar). The model application was also extended to model sour natural gas mixtures in equilibrium with an aqueous phase. Finally, the SAFT-based model was combined with a modified van der Waals and Platteeuw (vdWP) theory to predict water content of systems in equilibrium with hydrate. The theory was found to be in good agreement with experimental data found over a wide range of conditions, thus exhibiting the predictive ability of the proposed model.