On the impact of mass and heat integration on design and control of distillation column systems

The influence of mass and heat integration on design and control of three d ifferent column systems is investigated. Frequency dependent Relative Gain Analysis (RGA) is used to assess the merits of design modifications for the control loop decoupling of a binary heat-integrated distillation column. F or the separation of a ternary mixture, the direct sequence and one of its heat-integrated variants are investigated. Using steady-state sensitivity a nalysis, it is shown that the concentration of low boiling components in th e feed to the second column has a strong impact on the energy demand and co ntrollability of column sequences. An additional loop controlling this conc entration is recommended if large disturbances in feed composition are to b e expected. Where necessary, the results are verified by nonlinear closed-l oop simulation.