Process models and simulation methods can be used to simulate the fluidized-bed catalytic cracking unit (FCCU) process.a,b Likewise, kinetic or multivariate statistical models have been used. Rigorous non-linear reactor kinetic models have typically been applied to develop project design, support refinery planning, etc. However, kinetic models have had limited applications in maintaining FCCU operations and in optimization projects for many reasons. Kinetic models tend to be time-consuming and expensive to build and run. They are also difficult for the refinery engineers to maintain due to their complexity.