Phase equilibria for liquefied natural gas (LNG) as a multicomponent mixture

Abstract

Liquefied natural gas (LNG) has an increasingly important role in the global natural gas market. Global demand for natural gas will grow over the coming years. LNG is transported by ships to unloading points on the storage terminals. During the LNG unloading and storage processes some part of LNG evaporates into gas phase and causes changes in the composition of stored LNG. The main component of LNG is methane, the remaining components are primarily ethane, propane, butane and nitrogen. Depending on the participation of these components the basic thermodynamic parameters of LNG can significantly change. LNG is also product sensitive to changes of temperature. In order to better prediction of changes of individual parameters of stored LNG caused by changes of temperature and LNG composition vapor-liquid equilibrium (VLE) calculations are performed for cryogenic conditions using equations of state.