Collect. Czech. Chem. Commun. 1992, 57, 1362-1372

Modelling of the Multiphase Behavior of Methane-Ethane-Nitrogen Mixture at Low Temperatures with an Equation of State

Roumiana P. Stateva and Stefan G. Tsvetkov

Institute of Chemical Engineering, Bulgarian Academy of Sciences, acad. G. Bontchev str., bl. 103, Sofia 1113, Bulgaria


The paper discusses modelling of the multiphase behavior of the methane-ethane-nitrogen mixture, which is of a considerable interest for the natural gas and oil industries. The thermodynamic model is a modified Redlich-Kwong-Soave equation of state. The computer algorithm is based on a new approach to solving the isothermal multiphase flash problem, when the number and identity of the phases present at equilibrium are unknown in advance. The results demonstrate that Redlich-Kwong-Soave equation of state and the algorithm applied predict with reasonable accuracy the complicated phase behavior and the region of L1L2V equilibrium, observed in the experiment, of the methane-ethane-nitrogen system.