Modeling of Liquid 3 Vapor Equilibrium in Systems Including a Light Oil 3 Gas Component and Aromatic and Polyaromatic Hydrocarbons 1

The Victorov3Smirnova’s hole lattice quasichemical group-contribution model (HM) is used to simulate the vapor3liquid equilibrium in binary and ternary mixtures systems composed by aromatic (benzene, toluene) and polyaromatic (naphthalene, phenanthrene) hydrocarbons and light oil3gas components (carbon dioxide, hydrogen sulfide, nitrogen, methane, ethane, propane). Eighteen binary and two ternary systems are examined. New group parameters for these systems are estimated. The results of modeling are compared with the experimental data and those predicted by the Peng3Robinson equation of state. Designing of oil-and-gas production and processing requires reliable methods for predicting phase equilibria over wide temperature and pressure ranges in mixtures composed by a lot of components different in their chemical nature. Among the systems frequently occurring in petrochemical and coal-mining industries are binary mixtures of aromatic (or polyaromatic) hydrocarbons with typical light oil3gas components (lower alkanes, nitrogen, carbon dioxide, and hydrogen sulfide). In design engineering, cubic equations of state (EOS) of the van der Waals type hold much favor. For the above-indicated systems these are the Peng3 Robinson and Soave3Redlich3Kwong equations and their multiple modifications. All the equations of the van der Waals type used in practice are insufficiently universal and hardly suitable for description of the systems with long-chain, polar, and associated components. The questions related to developing equations of state and their practical use in modeling fluid phase equilibria are examined in the review [1]. Among the most valid (from the molecular standpoint) equations of state one can distinguish those based on the perturbation and numerical modeling theories and also on the lattice fluid models. One of the up-to-date lattice models was developed by Smirnova and Victorov [234]. In practice, the model can be used as its group-contribution modification. ÄÄÄÄÄÄÄÄÄÄÄÄ 1 Results were presented in part at the IV International Conference on Oil and Gas Chemistry, Tomsk (Russia), October 236, 2000. The common in all the group models is that molecules of components are represented as a combination of some chemical groups that are thought to provide additive contributions to thermodynamic characteristics of the system. The appeal of the group-contribution approach is caused by the fact that great diversity of molecules is composed by relatively small amount of chemical groups. As a result, compared to the number of molecules, considerably lesser amount of groups is needed to represent a great number of multicomponent systems occurring in the practice. Just these models are best suited for prediction of thermodynamic properties and phase equilibria in cases when experimental data are lacking. In this work, we selected the Victorov3Smirnova’s hole lattice quasichemical model (HM) and an equation of state derived on its basis. The HM was already successfully tested for modeling systems with specific intermolecular interactions, particularly, for pure and mixed fluids such as various hydrocarbons, alkanols, acetone, acetic acid, water, nitrogen, hydrogen sulfide, and carbon dioxide [2310]. The model proved to be quite adequate in simulating phase equilibria in diverse binary and multicomponent mixtures. In particular, it appeared to be useful in predicting phase equilibria in ternary systems water3subcritical vapor3 organic component [9]. Kuranov et al. [11] extended HM to include the electrostatic contribution and modeled the liquid3vapor equilibria at elevated pressure in the ternary systems CO23methyldiethanolamine3water and H2S3methyldiethanolamine3water