EXPERIMENTAL-DETERMINATION AND REPRESENTATION OF BINARY AND TERNARY DIAGRAMS OF N-HEXACOSANE, N-OCTACOSANE, AND N-HEPTANE

Accumulation of waxy deposits is a commonly occurring problem during e xploitation and transportation of paraffinic crude oils. Limitation of these undesirable solids or removal by methods such as addition of ch emical inhibitor, scrapping or heat tracing of flowlines, increase pro duction costs. A better knowledge of this phenomenon will make it poss ible to adjust process operating parameters and limit th operating cos ts. Thermodynamic models can be used in order to calculate the wax app earance temperature and the amount of solid deposit versus temperature . In these models, the crude oil is represented as a mixture of pure o r ''pseudo-components'' (which content several pure components). To de scribe the thermodynamic properties of those mixtures, data on pure co mponents and on their mixtures are necessary but they are very scarce for heavy components in the literature. This work is devoted to the st udy of a mixture of heavy components including two heavy n-alkanes (n- hexacosane, denoted C-26 and n-octacosane, denoted C-28) and a solvent (n-heptane denoted C-7). Measurements of solubility of C-26 and C-28 and of equimolar mixture of C-26 and C-28 in C-7, and an isothermal te rnary diagram of the mixture of the three components at 303 K are pres ented. Their calculations using simple expressions of Gibbs molar ener gy (NRTL and Redlich-Kister) are in good agreement with experimental d ata. The work allows to consider calculating complex systems with the only use of binary interaction coefficients.