A hierarchical coordination approach to the optimal operation of a sugar crystallization process.


Fawad Shamin, Reinaldo Hernández, Radoslav Paulen, Sebastian Engell


26th European Symposium on Computer Aided Process Engineering – ESCAPE 26


This paper describes a hierarchical decomposition approach for the optimal operation of a sugar crystallization process. The process consists of two sections: the evaporation section, which operates continuously, and the crystallization section, which consists of crystallizers that operate in a semi-batch mode according to a predefined recipe. A receding horizon nonlinear model predictive controller (NMPC) is designed for each crystallizer that steers the operation towards the economic optimum. A coordination scheme based on the Alternating Direction Method of Multipliers (ADMM) is proposed in order to establish a plant-wide optimal operation while the constraints imposed by the availability of shared resources (steam) are satisfied.