Easy Approach to Calculate Real Conversion and Yields from Hydroprocessing of Heavy Oils Plants

摘要

Calculation of conversion and yields is a very common task when studying a reaction at different evaluation scales (micro, bench, pilot, and commercial reactors). During experimentation with model compounds, the way in which conversion is determined is very well-known and quite easy, i.e., (initial moles of LR — final moles of LR)/initial moles of LR, where LR is the limiting reactant. If for any reason, LR is diluted with another compound, for instance, during the hydrodesulfurization of dibenzothiophene, n-decane is frequently employed as internal reference, and conversion is obtained by relating GC areas and initial concentrations of all compounds and assuming that n-decane remains unconverted under reaction conditions. However, when carrying out experiments or during commercial operation with real feeds, e.g., petroleum fractions, the way to calculate conversion may be sometimes not that easy. The difficulty comes from the fact that in some commercial processes other materials are fed into the reactor together with the feedstock, which in some cases makes it not so simple to perform mass balances. For example, to minimize sediment formation in commercial ebullated-bed vacuum residue hydro-processing, some aromatics-rich light streams, either produced in other units or in the same plant, are often used as diluents to the feed. The properties and composition of these nonconven-tional feeds introduce noise when determining conversion and other mass balance calculations. The aim of this work is to propose an easy methodology to determine "real" conversion and yields from data obtained in cases similar to those previously described.