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Thermodynamics of high‐pressure aqueous systems containing gases and salts
Author(s) -
Harvey Allan H.,
Prausnitz John M.
Publication year - 1989
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690350413
Subject(s) - osmotic coefficient , chemistry , thermodynamics , aqueous solution , brine , equation of state , activity coefficient , solubility , work (physics) , ion , salt (chemistry) , ionic bonding , organic chemistry , physics
This work provides a new method for calculating phase equilibria for systems where conventional activity‐coefficient models are not suitable. A procedure is presented for superimposing ionic effects on a conventional equation of state for nonelectrolytes. A modification of Born's equation is used to describe charging the ions; ion‐ion interactions are described with the Mean Spherical Approximation, coupled with an adjustable salt/solvent parameter that is obtained from osmotic‐coefficient data at room temperature. The equation of state is used to predict gas solubilities in aqueous salt solutions at high pressures. While this method produces qualitative agreement with the experimental solubility data, quantitative agreement requires a salt/ gas parameter obtained from Setchenow‐constant data. When Setchenow constants are used, agreement with experiment is good except at high salt concentrations, where salting‐out is usually underpredicted. Good results are obtained for phase equilibria in a natural‐gas/brine system at high pressures.