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Influence of n ‐paraffin composition on the aging of wax‐oil gel deposits
Author(s) -
Paso K. G.,
Fogler H. Scott
Publication year - 2003
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.690491223
Subject(s) - wax , paraffin wax , chemistry , chromatography , carbon fibers , carbon number , chemical engineering , materials science , composite material , organic chemistry , alkyl , composite number , engineering
An excess Gibbs free energy model is applied to investigate the influence of n‐paraffin composition on the aging behavior of wax‐oil gel deposits known to form in subsea petroleum transport pipelines. The aging of wax‐oil gels occurs by a counterdiffusion process where wax molecules with carbon numbers greater than a critical carbon number (CCN) diffuse into the gel matrix, and vice versa. Model crude oils were formulated to exhibit varying decreasing exponential distributions of n‐paraffin components in the range n‐C 9 to n‐C 53 . Deposition experiments were conducted using a laboratory cold finger apparatus simulating the cold wall of a subsea pipeline. Gas chromatography analysis of gel deposit compositions yielded experimental CCN values. A solid‐liquid‐phase equilibrium model, employing a modified version of UNIQUAC to compute solid‐phase component activity coefficients, was able to successfully predict the critical carbon number for a variety of model oil n‐paraffin compositions.