The project aims at developing a phenomenological model for describing distillation-column dynamics for multicomponent systems. For improving practical design and control of fractionation columns the model appropriately describes the critical nonlinear and distributed nature of column dynamics with a mathematical framework which is concise enough for on- line control (e.g. feed forward controllers), control system analysis, and column design. The ultimate goal is to make distillation columns operable at lower reflux ratios, and thus to lower energy consumption. Better fundamental understanding of column dynamics will make it possible to upgrade existing columns and design new ones which are less sensitive to disturbances. The research approach is based on the multicomponent coherence theory of simpler countercurrent separation processes such as fixed-bed chromatography theory. The theory is expanded by including the dynamics of reflux and reboil, interaction between two or more sections, and heat effects. The theory and the dynamic model are tested by comparison with experimental results. Experiments are carried out in an industrial laboratory with a pilot-plant-scale, computer controlled distillation column properly equipped with a fast gas chromatography system for on-line composition anonitoring.
