The common practice is to design chemical processes and their control systems in sequence. However, process design and control share important decisions, and when the process design is fixed there is little room left to improve the control performance. These observations suggest process design and control should be integrated.
The conventional framework for integrated design and control is to optimize the process, its control structure, and controllers, simultaneously. However, there are numerical as well as conceptual complexities associated with optimization of controllers. This research proposes integrated design and control based on perfect control. In the proposed optimization framework, an inversely controlled process model replaces the models of process and its controllers. Although the process and its control structure are optimized simultaneously, the complexities associated with controllers are disentangled from the problem formulation.
The thesis starts with introduction of the relevant concepts and review of literature in Chapters 1 and 2. Then, in Chapter 3, the steady-state and dynamic formulations of the proposed framework are presented. A steady-state inversely controlled process model achieves a higher degree of complexity reduction and ensures regulatory steady-state operability. However, at the price of higher modelling efforts, a dynamic inversely controlled process model ensures functional controllability as well. The proposed steady-state and dynamic optimization frameworks are demonstrated using several case studies. The proposed steady-state framework was applied for optimal control structure selection of a distillation train in Chapter 4 and integrated design and control of a reactive distillation column in Chapter 5. The proposed dynamic optimization framework was applied for the case of two heat-integrated series reactors in Chapter 6. The proposed optimization frameworks were successful in establishing the trade-off between control and process objectives. Finally, the thesis concludes with discussions, critical evaluation of the research and suggestions for future research in Chapter 7.