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A thermodynamic model for predicting wax formation in crude oils
Author(s) -
Hansen Jens H.,
Fredenslund Aa.,
Pedersen Karen Schou,
Rønningsen Hans Petter
Publication year - 1988
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.690341202
Subject(s) - wax , thermodynamics , metastability , gibbs free energy , surface tension , phase rule , crude oil , chemistry , polymer , thermodynamic equilibrium , phase diagram , phase (matter) , chromatography , organic chemistry , petroleum engineering , geology , physics
Most crude oils contain high molecular weight components, which at low temperatures may precipitate as a wax phase. This may cause plugging of pipes and numerous other problems. This paper presents a solid‐liquid equilibrium based model for the description of wax formation. The model for the Gibbs energy contains a contribution based on Flory's theory of multicomponent polymer solutions and a contribution from a metastable subcooled state which oil mixtures may attain. The latter is formulated in terms of the surface tension of the wax phase. Experimental wax appearance points (temperatures), WAP's, are reported for 17 different stabilized North Sea crude oils. The values predicted by the new model are in very good agreement with the experimental WAP's.