Consistency Relationships and Their Use in Model Uncertainty Determination

Fundamental mass and energy balances that exist in process systems can be used in modeling of the uncertainty description of the system. This allows us to define better uncertainty descriptions to be used in robust controller design. Uncertainty descriptions obtained from such an approach are tighter than unstructured descriptions because they are made to obey physical conservation laws. This explains how some ill-conditioned processes which seem difficult to control, can be controlled with relative ease. The approach is illustrated on a heat exchanger example and an ill-conditioned distillation column model.