Integrating real-time optimization into the model predictive controller of the FCC system

摘要

In this paper attention has been paid to the establishment of a proper real-time optimization strategy for the FCC unit. The majority of the approaches published in the literature make use of steady-state data. If the plant is highly disturbed updating the optimal operating point may not be easily achieved. In this study procedures are shown on how to overcome this problem and how to make use of the linear model predictive controllers (MPC) extending them to include optimization of the predicted steady-state operational point. Three such optimization strategies are presented that rapidly accommodate measured disturbances while avoiding offsets. The paper also shows results from the industrial implementation of one of these strategies at the refinery of Sao Jose in Brazil. The optimizing controller was integrated into the control package SICON, which was developed by Petrobras. Plant results show that the new controller is able to drive the process smoothly to a more profitable operating point overcoming the performance obtained by the existing advanced controller.