Determination of saturation pressures using experimental data of modified SC-CO2 extraction of crude oil by consistency test

• Published in: The Journal of supercritical fluids 2013-10, Vol.82, p.63-71
• Main Author: Rudyk, Svetlana
• Format: Article
• Language: English
• Subjects: Activity coefficient; Carbon dioxide; Consistency test; Consistency tests; Crude oil; Ethyl alcohol; Extraction; Mathematical analysis; Saturation; Vapor pressure
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2013.05.021

•Consistency test was applied to supercritical carbon dioxide crude oil extraction.•Unique combination of saturation vapour pressures using consistency test was determined.•Addition of co-solvents leads to the negative or positive deviations from ideal behaviour.•Area tests are applicable to complex systems and complex thermodynamic conditions. The current work aimed to perform a consistency test based on the Gibbs–Duhem equation in order to evaluate experimental results obtained by supercritical carbon dioxide extraction of crude oil modified with several co-solvents in pressures of 20–60MPa at 60°C. The collected oil represented a liquid phase fraction while the outgassing losses a vapour phase fraction obtained after extraction. The systems of crude oil and ethanol or methanol modified supercritical carbon dioxide exhibited negative deviations from the Lewis–Randall rule. The unique combinations of saturation vapour pressures that satisfied the consistency tests were determined for the systems with the co-solvents using the criterion of the even distribution of the data about zero line in the plots of area test. The obtained values can be used to determine the thermodynamic conditions where the maximum recoveries can occur and the regions where the multiphases exist. The current study demonstrates that the consistency test is able to evaluate supercritical carbon dioxide extraction data obtained at high pressures, when using a combination mode.