Synthesis and performance analysis of dividing wall distillation columns. 1. Advancing beyond the Kaibel column in quaternary separations with one reboiler and one condenser

Dividing wall columns (DWCs) enable the use of thermally coupled multicolumn configurations within a single distillation column shell, thereby reducing installation costs while retaining the energy benefits of thermal coupling. For four-component mixtures, the Kaibel, Satellite, and fully thermally coupled (FTC) DWC configurations are of particular interest. While the FTC design minimizes vapor duty, its structural complexity poses operational challenges. This study aims to address a critical gap in the literature by systematically quantifying the vapor-duty penalty of the industrially preferred Kaibel configuration and three satellite-column arrangements relative to the FTC configuration. Using our in-house user-friendly calculation software, we compare the minimum vapor duty across the 2500 feed compositions for each of the nine relative-volatility sets (a total of 22,500 distinct feeds). Our analysis shows that the satellite DWCs are practical alternatives to the more complex FTC configuration, frequently matching its vapor duty. In contrast, the simpler Kaibel DWC has the same low vapor duty over a much narrower operating window, because the Kaibel arrangement can be derived as a limiting case of the FTC configuration, highlighting the limitations of its simpler design. This study identifies the feed composition and relative-volatility space in which the Kaibel and each of the three satellite DWCs have vapor duties similar to those of the FTC DWC.