A Parametric Transfer Function Matrix for Packed Binary Distillation Columns Having Unequal Vapour and Liquid Capacitance

A general transfer function matrix (T.F.M.)has been derived for symmetrically built packed distillation columns, separating ideal binary mixtures. This T.F.M. is used to assess the adequacy of assuming zero vapour hold up in the mode and also, as previously proposed by the authors 1,2,3, of setting the ratio of vapour to liquid hold-ups to unity for predicting the dynamics of a general system. The analytical results are substantiated in frequency domain. It is noted that variations in the ratio of vapour to liquid hold-ups do not greatly influence the general dynamics of packed columns and that when this ratio is set to unity, the resulting simple model proposed by us, may adequately be used for the purpose of dynamic analysis and controller design.