Modeling the phase behaviour of bitumen/n-alkane systems with the cubic plus association (CPA) equation of state

Yechun Zhang, Alay Arya, Georgios Kontogeorgis, Harvey Yarranton*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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.
Original languageEnglish
JournalFluid Phase Equilibria
Volume486
Pages (from-to)119-138
ISSN0378-3812
DOIs
Publication statusPublished - 2019

Keywords

  • Phase behavior
  • Bitumen
  • n-alkane
  • Cubic plus association equation of state
  • Phase boundaries
  • Asphaltene yield
  • Phase compositions

Cite this

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title = "Modeling the phase behaviour of bitumen/n-alkane systems with the cubic plus association (CPA) equation of state",
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.",
keywords = "Phase behavior, Bitumen, n-alkane, Cubic plus association equation of state, Phase boundaries, Asphaltene yield, Phase compositions",
author = "Yechun Zhang and Alay Arya and Georgios Kontogeorgis and Harvey Yarranton",
year = "2019",
doi = "10.1016/j.fluid.2019.01.004",
language = "English",
volume = "486",
pages = "119--138",
journal = "Fluid Phase Equilibria",
issn = "0378-3812",
publisher = "Elsevier",

}

Modeling the phase behaviour of bitumen/n-alkane systems with the cubic plus association (CPA) equation of state. / Zhang, Yechun; Arya, Alay; Kontogeorgis, Georgios; Yarranton, Harvey.

In: Fluid Phase Equilibria, Vol. 486, 2019, p. 119-138.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Modeling the phase behaviour of bitumen/n-alkane systems with the cubic plus association (CPA) equation of state

AU - Zhang, Yechun

AU - Arya, Alay

AU - Kontogeorgis, Georgios

AU - Yarranton, Harvey

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - Phase behavior

KW - Bitumen

KW - n-alkane

KW - Cubic plus association equation of state

KW - Phase boundaries

KW - Asphaltene yield

KW - Phase compositions

U2 - 10.1016/j.fluid.2019.01.004

DO - 10.1016/j.fluid.2019.01.004

M3 - Journal article

VL - 486

SP - 119

EP - 138

JO - Fluid Phase Equilibria

JF - Fluid Phase Equilibria

SN - 0378-3812

ER -