Effect of control loop configuration on the bifurcation behavior and gasoline yield of industrial fluid catalytic cracking (FCC) units

This paper addresses the main problem associated with controlling the industrial fluid catalytic cracking units (FCC); the stabilization of the unstable high gasoline yield operating points. Six simple feedback control strategies are proposed using combinations of two manipulated and two controlled variables. The static and dynamic bifurcation behavior of the controlled FCC unit are examined in order to define the region of the controller gain values at which the desired operating point is globally stable. The results show that the performance of these units depends strongly on the structure of the control loop configuration. The analysis leads to quite useful insights on how to achieve stable operation of the process with high gasoline yield.