COMPARISON AND SUGGESTION OF BEST EOS'S TO PREDICT PHYSICAL PROPERTIES IN WAX/CATALYST SEPARATION BY SUPERCTITICAL HEXANE

Separation of a Fischer-Tropsch catalyst from its liquid products (wax) is one of the major challenges of slurry-bubble- column reactors. This problem, in fact, stems from the high viscosity and, therefore, the low catalyst separation rate of the reactor outlet wax. Supercritical Fluid Extraction is one of the best techniques to solve this problem, because of its excellent characteristics and also its high ability to modify the physical properties of the wax, such as viscosity and density.It should be noted that modeling and studying this separation process requirees the mentioned physical property Datum for the supercritical uid. But, calculation
of them cannot avoid mistakes in the near critical / supercritical region. In this work, after studying some theoretical correlations,
the best equations-of-state are proposed to predict the density, viscosity and thermal conductivity of light/heavy hydrocarbons and their mixtures. Then, the calculation of these physical properties is carried out for near-critical hexane and its mixture with wax by proposed EOS's. Results indicate that an increase of hexane in its near-critical operating condition has more in- uence on the physical properties improvement of wax when using the supercritical phase of the hexane (in comparison with gas and liquid states).