Modelagem termodinâmica do equilíbrio de formação de hidratos para sistemas contendo gases ácidos

Abstract

In this study, the van der Waals and Platteeuw model was coupled with Cubic Plus Association (CPA) equation of state (EoS) for equilibrium calculations in systems with clathrate hydrates, focusing on systems containing sour gases. A gaseous system is considered as and “sour gas” when it contains a significant amounts of H2S and/or CO2. A computer program developed in Fortran by Sirino (2017) was used. The metodology has been applied to simple (pure gases) and complex (binary and ternary) multicomponent systems. Including with the addiction of thermodynamic hydrate inhibitors as alcohols and glycols involving CH4, C3H8, CO2, H2S and N2. The mole fraction of components in all phases were obtained using a flash algorithm that has been developed in NUEM (Núcleo de Escoamento Multifásico – UTFPR), to improve the calculations accuracy. Furthermore, as a simplification, the CPA binary interaction coefficients were regressed as a linear function of temperature. The Kihara potential was chosen in the vdW-P hydrate phase modeling, being optimized to obtain a closer adjustment to the data taken from the available literature. The results obtained with the parameters optimization presented a significantly lower error ranges in a comparison with the CSMGem software, mainly for high pressures. The results presented good consistency with the experimental data taken from the literature.