(6b) Unfixed Wall: the Key to a Breakthrough in Dividing Wall Column Technology

Employing unfixed dividing wall proved to be the key to real breakthrough of dividing wall concept in the field of packed distillation columns. The flexibility regarding the positioning of easy assembling partition walls along the column extended the range of applications with respect to composition, relative volatilities and thermodynamic condition of three component mixture feeds and made practically feasible distilling four or more component mixtures in one shell. Similar benefits are expected from this highly flexible technology if applied in conjunction with trays, which is a more demanding task regarding the type and the size of potential applications. However, in addition to process related gains there are also numerous practical benefits of implementing unfixed wall concept in the field of tray distillation columns. It allows easy revamps of existing columns. Simple construction reduces costs significantly as well as the installation time. Welding work is reduced to an absolute minimum, i.e. there are no mechanical stresses introduced in the column shell through thermal expansion. No extra codes have to be followed regarding the tolerance requirements of the dividing wall. These and other, process and mechanical design/operation related benefits will be demonstrated using practical examples.