Demonstration of non-linear model predictive control of post-combustion CO₂ capture processes

Nonlinear model predictive control applications have been deployed on two large pilot plants for post combustion CO₂ capture. The control objective is formulated in such a way that the CO₂ capture ratio is controlled at a desired value, while the reboiler duty is formulated as an unreachable maximum constraint. With a correct tuning, it is demonstrated that the controllers automatically compensate for disturbances in flue gas rates and compositions to obtain the desired capture ratio while the reboiler duty is minimized. The applications are able to minimize the transient periods between two different capture rates with the use of minimum reboiler duty.