Module 13. Distillation Control

Distillation remains the most common method of separating chemical components from a mixture. In this module, we provide a simple example of a binary distillation column that has behavior illustrative of more complex columns. The goal is to better understand the dynamic behavior of multivariable, interacting systems. After studying this module the reader should be able to do the following:

• Understand the different control loops associated with distillation operation

• Understand the importance of input "direction" when making step input changes

• Understand how an input "direction" affects the magnitude and "direction" of the resulting output change

• Interpret SVD results in terms of these sensitive directions

• Consider failure sensitivity when designing controllers

The sections of this module are as follows:

M13.1 Description of Distillation Control

M13.2 Open-Loop Behavior

M13.3 SISO Control

M13.4 RGA Analysis

M13.5 Multiple SISO Controllers

M13.6 Singular Value Analysis

M13.7 Nonlinear Effects

M13.8 Other Issues in Distillation Column Control

M13.9 Summary