Integrating systems design and control using dynamic flexibility analysis

Currently, chemical process design and process control are separate disciplines assisting process development at different stages. Design and control decisions are made separately despite the common objective of dissipating the impact of uncertainty to ensure robust plant operation. Experience suggests that designing processes for flexibility against disturbances or parameter variations without considering dynamics under actual control feedback does not guarantee robust performance. Thus, it appears advantageous to address process design and control decisions simultaneously for maximizing performance in face of operational and model uncertainty. Realistic high-performance processes should be optimal in their dynamic operation with realizable control. The lack of integration between design and control objectives at the conceptual level is addressed here. The proposed procedure finds optimal trade-offs between design and control decisions, based on process dynamics and advanced control. A major innovation is a novel embedded control optimization approach. It suggests a two-stage problem decomposition leading to a massive reduction of problem size and complexity. Integration of design and control is expected to have a broad impact on high-performance systems operated close to their limits. Two case studies demonstrate the suitability of the methodology. (c) 2007 American Institute of Chemical Engineers.