FLASH CALCULATIONS FOR A CRUDE OIL BY CONTINUOUS THERMODYNAMICS

Continuous thermodynamics is a suitable concept for performing phase equilibrium calculations of complex multi-component mixtures. In contrast to the traditional pseudo-component method, the continuous distribution density function obtained by the characterization experiment is used directly for the thermodynamic calculations. This paper describes the application of continuous thermodynamics to flash calculations for a crude oil. In the simple version the coexisting phases are assumed to behave ideally. In the refined version the real behavior is accounted for describing non-aromatics and aromatics as two different continuous ensembles. It proves possible to separate in the calculations the problem of the compositions in the coexisting vapor and liquid phases from the problem of the equilibrium temperatures. For the compositions exact explicit equations are provided. To obtain the equilibrium temperatures the numerical solution of only one equation (in the simple version) or of a system of only three equations (in the refined version) is required. The refined as well as the simple version lead to good coincidence with experimental data