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Title: High pressure vapor-liquid equilibria involving mixtures of nitrogen, carbon dioxide, and hydrocarbons

Miscellaneous ·
OSTI ID:7081339

A new high pressure vapor-liquid equilibrium apparatus has been designed and constructed with the capability of measuring equilibrium phase compositions and densities of coexisting phases at constant temperature and/or pressure. The apparatus is a double recirculation apparatus with a maximum temperature and pressure of 150 C and 5000 psia, respectively. The main components of the apparatus consist of a through-windowed Ruska cell, two magnetic recirculation pumps, and two Mettler-Paar vibrating-tube density meters. The systems selected for study are binary and ternary mixtures of nitrogen, carbon dioxide, and hydrocarbons. These systems were chosen because of industrial and academic interest in modeling the phase behavior of asymmetric mixtures containing supercritical components. The apparatus was tested by measuring the carbon dioxide + n-butane system will excellent agreement observed between our results and published data. The other chosen systems are: nitrogen + n-butane, nitrogen + carbon dioxide + n-butane, carbon dioxide + cyclohexane, nitrogen + cyclohexane, and nitrogen + carbon dioxide + cyclohexane. Fits of the data with the Peng-Robinson equation of state and van der Waals one-fluid mixing rules were acceptable, with the exception of the nitrogen + n-butane isotherms. Use of the Soave-Redlich-Kwong and Teja-Patel equations of state did not improve the fit, so modeling efforts focused on the mixing rules. Best results were obtained with the two-parameter van der Waals one-fluid mixing rules and Xu-Sandler a and b parameters, although similar results were observed with Lee-Sandler density-dependent mixing rule. Liquid density fits were significantly improved with the use of Xu-Sandler a and b parameters.

Research Organization:
Delaware Univ., Newark, DE (USA)
OSTI ID:
7081339
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English