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Abstract The cubic-plus-association equation of state was applied to model the phase behaviour of bitumen/ n -alkane systems including saturation pressures, liquid-liquid boundaries, yields, and phase compositions. Yield is defined here as the mass of bitumen in the heavy phase divided by the mass of bitumen in the feed. To implement the model, the bitumen was divided into a set of pseudo-components based on a distillation assay and either the n -pentane insoluble content of the oil (CPA-C5 approach) or the propane insoluble content (CPA-C3 approach). The pseudo-components in the solvent insoluble part of the oil were defined as self-associating components, all other pseudo-components were non-associating. The critical properties and acentric factor for each pseudo-component were determined from established correlations. A set of CPA parameters was then developed to fit the available phase behavior data. The self-associating pseudo-components were assigned a distribution of self-association energies in order to capture the sequential partitioning of asphaltenes to the heavy phase upon solvent addition or in different solvents. Both approaches matched the phase behavior data for mixtures of bitumen with n -pentane and higher carbon number n -alkanes almost to within the experimental error. The CPA-C3 approach also matched the phase behavior data for mixtures of propane and bitumen. The CPA-C5 approach could not match the yield data for propane diluted bitumen but was more straightforward to implement and was less computationally intensive because it employed fewer self-associating components. To apply either approach to another oil, only the self-association energy of the self-associating pseudo-components need be adjusted. The cross-association energy between the solvent and the self-associating pseudo-components must be tuned for any new solvent. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses a procedure to determine the dew and bubble point temperatures and pressures for mixtures. The procedure uses the fact that isochors change slope when they pass from the single-phase to the two-phase region. A selection of the single- and two-phase region data points results from a statistical analysis. We can determine the phase boundary temperatures and pressures within 0.45% and 0.04%, respectively. We have applied this procedure to determine the temperatures and pressures at the phase boundaries of binary and multicomponent mixtures. The major advantage of the method is the compositions are known from gravimetric construction. [Copyright &y& Elsevier]