MPC vs. PID. The advanced control solution for an industrial heat integrated fluid catalytic cracking plant

The modern process plants are continuously improved for a flexible production and for maximization of the energy and material savings. These plants are becoming more complex with strong interactions between the process units. Consequently, the failure of one unit might have a negative effect on the overall productivity. This situation reveals important control problems. Another problem is that the traditional techniques developed by now can hardly handle all the control problems that appear in modern plants. However, the appearance and the continuously development of the advanced control techniques provide better solutions for plants control at any level of complexity of the process. In this study a complex heat integrated fluid catalytic cracking (FCC) plant was used for comparing a model predictive control (MPC) strategy with the classical PID control strategy already implemented in the real plant. The study results revealed that the MPC controller was capable to maintain the variation of the controlled variables much closer to the set points than the classical PID controllers. The present work shows that it is possible to save equipment and energy costs. Moreover, it is well known that using a MPC strategy the plant can be exploited at its maximum capacity.