Dynamic simulation of high-index models of batch distillation processes

The dynamic modeling of batch distillation columns frequently leads to a mixed system of differential and algebraic equations (DAEs) with differential index greater than one, and this particular feature has many implications on the resolution strategy adopted. As the number of stages and components can be arbitrarily high, those mathematical models can be large scale systems, and the analysis of the system prior to numerical resolution can be cumbersome. Additionally, the consistent initialization step can pose a nontrivial numerical task. For the numerical resolution of this model it is employed the computational code under development at PEQ/COPPE/UFRJ and DEQUI/UFRGS. This code employs Automatic Differentiation (AD) tools to perform index reduction and consistent initialization with minimum interference of the user. The resulting consistency system is solved and the numerical integration of the final index-one DAE is accomplished by means of the integration code DASSLC.