Rigorous dynamics model of distillation columns

For distillation columns, dynamic models which consider variable pressure and vapor holdup were studied. A most rigorous model which used the vapor hydraulic equation was studied with implicit methods. Vapor holdup must be considered in high pressure columns in order to predict dynamic responses accurately. The effect of pressure changes on the tray was only important for the vacuum column, particularly when heat input disturbances occurred. The rigorous vapor hydraulic model was shown to be useful, despite the fact that it is extremely stiff, provided an implicit integration algorithm (LSODES) is employed.