Plantwide Control Based in Economic Conditions and Operability

GONZALO MOLINA AND MARTA BASUALDO.

Río Gallegos, Argentina.

Congreso; XII Reunión de Trabajo en Procesamiento de la Información y Control (RPIC),; 2007

Universidad Nacional de la Patagonia Austral

In this work the study of a simple plant formed by a fixed temperature and liquid face reactor, a distillation column and a material recycle is proposed. This academic case was extensively studied in the literature, even though its simplicity, allows to understand the main interaction effects and changes of time response due to the recycle existence. Different control schemes, tested before and based on achieving the optimum, since the economic point of view are analyzed here. However, the steady-state study shows that most of them present problems to handle properly load changes. Most of the proposed strategies cannot deal with the trade-off between economic and operability objectives specially for this kind of plants where the fast increase of the material recycle, recognized as “snowball effect” (SE), often occurs. Thus, in this work a control strategy for reducing the SE achieving good operability and profitable working point is discussed. Several results, confronted with other methodologies, obtained from the steady state and dynamic analysis are presented in order to demonstrate the potentiality of the proposed technique.