Determination of limit of stability profiles for liquefied natural gas: a thermodynamic approach

Abstract

Efficient design, operation, handling, and transportation of natural gas as liquefied natural gas (LNG) are controlled by its phase behavior. A phase, in a non-reacting system, is known to be stable when it is at its lowest Gibbs energy; an alternative criterion to the minimization of the Gibbs energy is presented for phase stability status determination of pure systems and mixtures. On this premise, the stability limit determination method by the Helmholtz stability criterion was employed for the determination of stability limits which were used to successfully generate stability limit profiles for LNG and its constituents. To further investigate the metastable region, a new and robust model was developed and successfully used to produce vapor and liquid spinodals as well as binodal curves for the LNG constituents. The model accurately predicted the critical points and was shown to be in very close agreement with the available predicted and experimental results.