(163d) Control Structure Selection for a Dividing Wall Column

A distillation process plays an important role in separating materials but it consumes enormous amount of energy in chemical processes. As an alternative energy saving process, the petlyuk column was proposed in 1950s. The petlyuk column can reduce energy consumption by thermally integrating two columns but integration of two columns involves the extra capital cost. To solve this problem, Dividing Wall Column (DWC), which is conceptually the same as the petlyuk column, has been developed by installing a vertical wall in the middle part of the column.

However, industry has been hesitant to use DWCs because the DWC has control and operation problems. The reason is that general knowledge on the dynamic behavior of the DWC is still lacking because many studies focused on specific processes and materials. To make general design standard for control structure of the DWC, general knowledge of dynamic properties for the DWC is required.

In this study, the dynamic behaviors of the DWC with the various feed compositions and feed materials are studied. By changing the feed components, which have different relative volatilities and mole fractions in feed, the influences of their distribution coefficients on the dynamics and the separation properties of the DWC are examined. Based on the open loop behaviors, reasonable control structures are proposed to deal with various feed conditions. As a result, the properties of DWC and separation performance can be easily predicted by inspecting the composition and the relative volatilities of feed materials.

Acknowledgement

This work was supported by 2006 Energy?Resource Technology Development Program from KEMCO and Center for Ultramicrochemical Process Systems sponsored by KOSEF.