Modeling and optimization of a fluidized catalytic cracking process under full and partial combustion modes

Abstract

A process optimization system, which consists of a steady-state process model, a model parameter estimator and a process optimizer for a fluidized catalytic cracking (FCC) process under full and partial combustion modes, is presented in this paper. First, mathematical modeling was carried out for the reactor, regenerator, main-fractionator, and most of auxiliary units including the feed pre-heater, catalyst cooler, air blower, wet gas compressor, stack gas expander, boilers, and valves. Then, the resulting steady-state model was utilized to develop the model parameter estimator and the process optimizer both of which adopt a successive quadratic programming algorithm to efficiently locate the optimum solutions. The parameter estimator can estimate up to 52 model parameters in order to validate the process model by reducing process–model mismatch. The process optimizer maximizes the economic objective function defined as the difference between the total value of products and the cost of feedstock and utility under 30 operating constraints. The developed optimization system was applied to several optimization cases to maximize the economic profit of the FCC process operated in the full and partial combustion modes and the optimization results were extensively compared and analyzed between the combustion modes. It is expected that the proposed steady-state model, parameter estimation and optimization methods can be utilized to optimize and design modem-type FCC processes under full and partial combustion modes.