Simulink Control Design™ - MathWorks

Decoupling Controller for a Distillation Column

This example shows how to use looptune to decouple the two main feedback loops in a

distillation column.

Distillation Column Model

This example uses a simple model of the distillation column shown below.

Figure 1: Distillation Column

In the so-called LV configuration, the controlled variables are the concentrations yD and

yB of the chemicals D (tops) and B (bottoms), and the manipulated variables are the reflux

L and boilup V. This process exhibits strong coupling and large variations in steady-state

gain for some combinations of L and V. For more details, see Skogestad and Postlethwaite,

Multivariable Feedback Control.

The plant is modeled as a first-order transfer function with inputs L,V and outputs

yD,yB:

Decoupling Controller for a Distillation Column