Analysis of different control possibilities for the divided wall column: feedback diagonal and dynamic matrix control

This work addresses the control of the divided wall column (DWC) as a basic issue to be considered when this kind of distillation arrangement is used to take profit of its potential to reduce energy consumption. Different con trol structures of diagonal feedback control are compared using multiple in put multiple output (MIMO) linear analysis tools in the frequency domain. A controllability analysis of the process is done for the separation of diff erent mixtures and for different operating conditions, including optimal op eration. As a result, it is seen that a trade off appears between energy mi nimisation and controllability. As an alternative, application of dynamic m atrix control (BMC) to the DWC is also evaluated. Through simulation, the a bility of DMC for disturbance rejection and setpoint tracking is studied an d compared with that of the feedback diagonal control. Important limitation s of using DMC for the composition control of the DWC are finally highlight ed. Q 2001 Elsevier Science Ltd. All rights reserved.