The interactions of design and control: double-effect distillation

A general, rigorous dynamic model is described for studying the interactions of design and control in a double-e€ect distillation system. Two approaches are adopted. In the ®rst, the steady-state process design and the control system are optimized sequentially; potential operability bottlenecks are identi®ed and the economic advantage of double-e€ect systems over conventional single col- umn systems is demonstrated. In the second approach, the process design and the control system are optimized simultaneously leading to a more economically bene®cial system than that obtained using the sequential approach.