The distillation column shown in the drawing is used to distill a binary mixture. Symbols x, y, and z denote mole fractions of the more volatile component, while B, D, R, and F represent molar flow rates. It is desired to control distillate composition y despite disturbances in feed flow rate F. All flow rates can be measured and manipulated with the exception of F, which can only be measured. A composition analyzer provides measurements of y.
(a) Propose a feedback control method and sketch the schematic diagram.
(b) Suggest a feedforward control method and sketch the schematic diagram.