ABSTRACT
Feed quality is considered the most influential single factor affecting the fluidized catalytic cracking (FCC) unit performance. Chemical composition of the FCC feed affects yields and the quality of products. The FCC feed properties strongly depend on two factors: the geographic source of the crude and its initial preprocessing. To make things even more complicated, FCC feeds are usually blends of multiple feed sources and refinery recycle streams, some of which are of very poor quality. Therefore, knowing the molecular composition and concentrations of a complex feed aids in optimizing FCC unit operations, and also supports the process of catalyst selection and product yield predictions. In general, the typical analytical techniques for feed characterization provide helpful information about feed quality, but they are not adequate to provide the identities and concentrations of the molecules in commercial FCC feeds. Over the years, methods have been developed, mostly in the form of heuristic correlations, to predict important FCC feed properties such as hydrogen content, type of carbon (aromatic: Ca, paraffinic: Cp, and naphthenic: Cn), molecular weight, and so on, with a goal to relate these feed quality characteristics to product yields and qualities. However, the range for which these correlations were developed, and the assumptions and mathematical manipulation involved in the derivation of such formulas limit the use of these techniques.
