Abstract

This study presents a thermodynamic framework for predicting hydrate equilibrium pressure of gas species including methane, ethane, propane, nitrogen, carbon dioxide and hydrogen sulfide and their mixtures. For this purpose, Peng–Robinson–Stryjek–Vera equation of state (PRSV-EOS) along with modified Huron-Vidal (MHV1) mixing rule and UNIQUAC model were employed to calculate fugacity and activity coefficient of water in equilibrated fluid phases. To represent phase behavior of solid hydrate, a modified version of van der Waals and Platteeuw (vWd-P) model was utilized which accounts for guest interaction with water molecules beyond first shell of cavity and also asymmetry of encapsulated molecules and cage structure. In addition, dissolution of gas compounds in aqueous phase and subsequent non-ideality of water was taken into account. It was realized that both physical phenomena are of marked influence on the prediction accuracy.In contrast to conventional modelling approaches which scarify some part of equilibrium data to regress some adjustable parameters, advantageously, our model does not require any pre-matching. It was observed that present framework gives accurate prediction for equilibrium pressure of hydrates of CH4, C2H6, C3H8, CO2, N2 and H2S with overall average absolute percent deviation (AAPD) 3.2, 3.4, 3.7, 1.5, 2.8 and 1.3, respectively. Also, incipient pressure of hydrate formed by binary gas mixtures comprised of aforementioned single components could accurately be predicted by proposed approach, which is detailed in the manuscript. Overall, formation pressures predicted by proposed modelling approach are more accurate (or at least comparable) to outstanding models presented in the hydrate literature.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.