Design and control of recycle systems by non-linear analysis

Design and control of recycle systems must be integrated at an early design stage. By placing together the pieces of the design puzzle we developed a novel methodology that allows the screening and selection of feasible integrated designs at an early stage. The generic structure is the Reactor-Separator-Recycle (R-S-R) system. Multiple steady states are possible and a minimum reactor volume is required. The behaviour depends on the reactor size and plantwide control structure. Larger reactors behave better than smaller ones. A clear distinction is made between self-regulation and regulation-by-feedback control structures. For some complex reactions, the simple self-regulation feed policy is effective and ensures the desired selectivity pattern. This study integrates the results into a new reliable methodology for design and control of recycle systems.