A Systematic Study of Cubic Equations of State with van der Waals Mixing Rules and Different Combining Rules in Predicting the Densities of LNG and Natural Gas Model Systems

Year 2019, , 107 - 116, 23.05.2019

Monther Al-manthari Majid Al-wadhahi Khashayar Nasrifar G. Reza Vakili-nezhaad

https://doi.org/10.5541/ijot.528164

Cited By: 3

Abstract

Cubic
equations (EoSs) of state are successfully used in petroleum and natural gas
industry. In order to extend these equations to mixtures, van der Waals mixing
rules with Lorentz-Berthelot (LB) combining rules are often employed; however,
the accuracies of these EoSs in predicting the densities of hydrocarbon mixtures
are not adequate. The main objective of this study was comparing 13 EoSs
coupled with 10 combining rules in predicting the densities of hydrocarbon mixtures.
Binary and ternary liquid mixtures, LNG mixtures and synthetic natural gas
mixtures comprising 752 data points were collected and used in this study.
Results revealed that for predicting the liquid densities of binary and ternary
mixtures, the Schmidt and Wenzel (SW) EoS coupled with Hudson-McCoubrey (HMC)
or LB combining rules are the best among the others. The SW EoS coupled with
the LB combining rules were also the best in predicting the densities of the LNG
mixtures. Additionally, the LB combining rules are the best in predicting
natural gas mixtures densities using the Patel and Teja (PT), SW and
Patel-Teja-Valderrama (PTV) EoSs. In general, it was found that the Redlich-Kwong
(RK) family EoSs, SW and Trebble-Bishnoi-Salim (TBS) EoSs are best coupled with
the LB combining rules. However, the Peng and Robinson (PR) family EoSs with Halgren
(HHG) combining rules were in better agreement with experimental data. The Waldman-Hagler
(WH) combining rules lacked predictability when coupled with the most EoSs.

Keywords

Density, Natural Gas, Hydrocarbon, Equation of State

References

• Reference 1:Prof. G. Ali [e-mail]
• Reference 2:Prof. Vahid [e-mail]
• Reference 3:Dr. Angel [e-mail]