Control and Optimisation of a Fluid Catalytic Cracking Process: An Industrial Case
Systematic methods and tools for managing the complexity
Process Control (T4-8P)
Keywords: Fluid catalytic cracking, Industrial process, Process control, Process optimisation, Nonlinear dynamics
Fluid Catalytic Cracking (FCC) is an important refinery process. Therefore the economical incentives to operate near optimal conditions are high, however FCC units optimal performance is usually achieved near physical and operating constraints of this process, which makes the FCC a challenging task for control and optimisation studies.
Several works on the control of FCC units have been conducted and several authors have published papers on this subject. Among others, Alvarez-Ramirez et al. (2004) presented recently a linear multivariable cascade control scheme for composition regulation at the riser outlet. Ansari and Tadé (2000) presented a nonlinear constrained multivariable control algorithm and compared it with Dynamic Matrix Control (DMC), a linear Model Predictive Control (MPC) strategy applied typically to industrial processes. Besides using their dynamic model for nonlinear control, Ansari and Tadé (2000) used it also to calculate the economic optimal values of the key operating variables in the FCC process; namely the feed rate, reactor temperature and feed preheat temperature.
A model that can predict both the steady and dynamic state of an UOP FCC with High Efficiency Regenerator was developed and compared to industrial data from an operating unit. Regulatory control based on PI control loops was also implemented. These control loops were chosen to be the same as the ones in the operating unit. The current work presents different strategies of model predictive control (MPC) implemented and tested with economical objectives. Besides process operating conditions optimisation variables such as atmospheric residue incorporation are optimised.
Alvarez-Ramirez, J., Valencia, J. and Puebla, H. (2004). Multivariable control configurations for composition regulation in a fluid catalytic cracking unit. Chem. Eng. J., 99, 187-201.
Ansari, R.M. and Tadé, M.O. (2000). Constrained nonlinear multivariable control of a fluid catalytic cracking process. J. Process Control, 10, 539-555.
Presented Tuesday 18, 13:30 to 15:00, in session Process Control (T4-8P).
