Future directions in modelling the FCC process: An emphasis on product quality

A new generation FCC process model has been developed that describes fundamental cracking chemistry of FCC feedstocks using over 3000 molecular species. FCC reaction chemistry is specified using the methods of structure-oriented-lumping (SOL) with over 60 reaction rules. Application of these rules results in a complex network of over 30,000 elementary chemical reactions. Both monomolecular reactions such as cracking, isomerization, and cyclization and bimolecular reactions such as hydrogen transfer, coking, and disproportionation are included. The effects of thermal cracking and metals-catalyzed dehydrogenation are also represented. Reactivity relationships have been developed to reduce the number of parameters required to specify the kinetic model. The kinetic parameters are regressed from data spanning a wide range of FCC process conditions, feed compositions, and catalyst formulations. The riser kinetic model is coupled with equipment models for key FCC components to form an integrated FCC process model. The model accurately predicts product yields, product composition, and product quality over a wide range of FCC process conditions and is capable of predicting the complex non-linear phenomena exhibited in commercial FCC operations such as steady-state multiplicity. The model can be used to predict the quality of FCC products made from different crudes as well as to scope novel processing schemes for improving FCC product quality. (C) 1999 Elsevier Science Ltd. All rights reserved.