ANALYSIS OF LIQUEFIED NATURAL GAS THERMODYNAMIC PROPERTIES INVOLVING PHASE EQUILIBRIA CALCULATIONS

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-57-5 / ISSN 1314-2704, June 28 - July 6, 2016, Book1 Vol. 3, 729-736 pp

ABSTRACT
Role of Liquefied Natural Gas (LNG) will increase in the next years in the global natural gas market. LNG is transported by ships to unloading points on the storage terminals. In the process of Liquefied Natural Gas storage the thermodynamic stability and determination of phase equilibrium is one of the most important issues associated with calculating of multi-component mixtures thermodynamic properties. During the LNG storage process some part of LNG evaporates into gas phase and causes changes in the composition and consequently thermodynamic properties of stored LNG. Depending on the participation of these components the basic thermodynamic parameters of LNG can significantly change. LNG is also sensitive to variability of temperature. Changes in the composition of the stored LNG may lead to stratification and instability called roll-over. For better prediction of variability 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 different thermodynamic models involving equations of state.

Keywords: LNG, liquefied natural gas, thermodynamic properties, VLE calculations, phase equilibrium