COMPOSITION AND VISBREAKABILITY OF PETROLEUM RESIDUES

An intensive experimental study has been performed on atmospheric residues from three crude oils (Rospo di mare, Belaym, Es Sider) in order to develop general correlation between visbreaking feedstock characteristics, yield and quality of products. The study allows to assess that the feedstocks rich in asphaltenes, resins and polars exhibit higher kinetic constants at low temperatures but lower kinetic constants at the temperatures normally employed in visbreaking units. In comparison with heavy crude residues, light and paraffinic feedstocks have higher activation energy, higher gasoil selectivity and lower gas production. Correlations have been set up between yield of light valuable products, stability of the visbroken residues and the composition of asphaltene and malthene fractions of the feedstock. Increasing the difference between aromatic carbon content of asphaltenes and malthenes of the feedstock, decreases the stability of the visbroken residues obtained at the same operating conditions and decreases the maximum conversion allowed by the visbreaking process.