(139b) Bridging the Know-How Gap - Hydraulic Design of Packed Dividing Wall Columns

By virtue of its design a Dividing Wall Column (DWC) minimizes energy and equipment as well as plot area requirements of three and more component separations by distillation, which makes it to the most sustainable among distillation technologies. Although proven and well established in practice, and highly appealing regarding energy and capital saving potential, the number of industrial applications of DWCs is still limited. Indeed, as elaborated in greater details elsewhere, e.g. Jansen et al., Chemical Engineering, August 2014, 40-48, a DWC is an atypical distillation column and there are certain process and mechanical design and operation-related concerns and potential constraints that may discourage inexperienced practitioners and make them reluctant to consider design and implementation of a DWC in prospective applications.

In the meantime, many process engineers have developed skills and are capable of using available tools within commercial software packages to simulate performance, i.e. to establish reflux and stage requirements of a DWC. However, what is not readily available in commercial software packages is a proven DWC dimensioning method. Indeed, a reliable hydraulic design method is needed to translate performance simulation results into diameter(s) and height of the shell of a new DWC, or to examine appropriateness of an existing column shell in a retrofit case, including detailed internal layout and proper dimensions of normal and partitioned sections, depending on chosen type and size of structured packing and auxiliary equipment. This must be done with certain rigor if one wishes to arrive at a reliable basis for evaluation of cost-effectiveness of both new DWC designs and retrofits.

To provide basis for filling the existing know-how gap, the present paper addresses all relevant aspects of packed DWC dimensioning, using engineering tools available in public domain. Emphasis is on equipment choice and a predictive model that enables accurate estimation and proper balancing of the pressure drop in parallel sections. The latter being the key to successful design and operation of DWCs. Capability of quantification in this respect opens the door for exploration of possibilities for expansion of the application window of DWCs, both as a new design to enhance potential benefits and as an energy saving retrofit option.