Comparing hydrocracking models: Continuous lumping vs. single events

Development of models for industrial hydrocrackers has received a great amount of attention by the scientific community over the past decades. Two fundamentally different modelling approaches are compared in this paper: a continuous lumping model with three families (paraffins, naphthenes, and aromatics) and a single events microkinetic model. The aim is to demonstrate the differences in the capabilities of the two modelling frameworks. Both models are capable of simulating experimental data from hydrocracking of a pre-treated Vacuum Gas Oil in a pilot plant at industrial conditions. The continuous lumping model provides better results of the macroscopic effluent characteristics, such as yield structure and PNA (Paraffin, Naphthene, Aromatic) distribution in the middle distillate cut. It requires only the feed SIMDIS (Simulated Distillation) and PNA composition to be known. The single events model, on the other hand, provides information which is not available in a simple continuous lumping model. An analysis of the reaction kinetics of paraffins and mono-naphthenes is performed to demonstrate this aspect. The single events model is far more complex and computationally expensive than the continuous lumping model. In conclusion, the two approaches should be considered complementary rather than competitive. In conjunction, they can be used to balance the drawbacks of each individual modelling approach.