Structural analysis in the dynamical modelling of chemical engineering systems

The dynamical modelling of physical (bio-)chemical processes based on first principles considerations is analysed from a structural point of view. Bas ed on a classification of the variables and equations that occur in such mo dels, we propose a general framework that can help to organise the model in a transparent way and to analyse efficiently its solvability properties. W e show that a well-known tool in the theory of nonlinear dynamical systems, the Zero Dynamics Algorithm, can be used in the analysis of higher index m odels and also in index reduction. The symbolic computations involved in th is algorithm are readily available in the form of nonlinear system analysis packages. The proposed methods are illustrated by a few simple concrete ex amples.