Integrated Scheduling and Control of Continuous-Time Blending Processes
Abstract Scheduling and control of multiproduct blending processes is important in many fields of process systems engineering. It is characterized by nonlinear process dynamics, numerous product specifications and discrete state variables. Due to the high complexity of the resulting mixed-integer dynamic model, integrating all these properties simultaneously in continuous time has not been addressed for blending processes in literature so far. In this contribution, a novel modeling framework for integrated scheduling and control of continuous-time multiproduct blending problems is presented. The framework incorporates the flexible handling of production and transition stages. Moreover, product demand is treated as continuous-time specification of the production process with possible discrete demand due dates. The resulting non-convex mixed-integer dynamic optimization problem is solved by means of a single-shooting method embedded in a branch & bound framework. The novel methodology is illustrated by means of a blending case study with a variety of feed streams with different property compositions and numerous specifications for each of the three manufactured products.