DYNAMIC SIMULATOR FOR A MODEL-IV FLUID CATALYTIC CRACKING UNIT

The purpose of this paper is to make available to the process control research community, in academia and industry alike, a detailed and realistic industrial simulation system for evaluating and teaching new and existing methods in system analysis, identification, control and on-line optimization. A mechanistic dynamic simulator is presented for the reactor/regenerator section of a Model IV fluid catalytic cracking unit (FCCU). The model is sufficiently complex to capture the major dynamic effects that occur in an actual Model IV system. It is multivariable, strongly interacting and highly nonlinear. The simulator includes all important system constraints; multiple hard equipment constraints and operating constraints, arising from economic, environmental and safety considerations, are present. Considerable incentive exists to improve the economic performance of FCCUs through the application of advanced control and/or optimization strategies. Unmeasured disturbances in feed composition and changes in ambient conditions (as well as other disturbances) move the location of the constrained optimum for feed throughput. A control/optimization system must locate and track this constrained optimum while regulating against disturbances. An ACSL (Advanced Continuous Simulation Language) program is available from the authors for integrating the FCCU model. Instructions for implementing advanced control algorithms, using Fortran subroutines, are also provided with the program, as well as instructions for executing ACSL runs with preprogrammed disturbances. A complete set of model equations is provided in this paper.