The reactive dividing-wall column (RDWC) combines a reactor and a dividing-wall column (DWC) in a single column shell. Lately, various reaction systems have been proposed for the RDWC, but only little general knowledge has been published on the RDWC so far. The fundamental mechanisms of the RDWC are analyzed and a profound process understanding is deduced based on principal aspects of reactive distillation and the DWC. Fields of application and insights into the key factors for an energy-efficient operation are systematically derived. A semi-shortcut method is proposed to determine the minimum vapor demand of the RDWC and its energy-saving mechanism is explained. Thereby, process engineers can evaluate already during the process synthesis whether the RDWC is a promising option. Furthermore, they can quantify the energy savings quickly and get an understanding of the key factors for an energy-efficient column design and operation.

The implementation of a vertical dividing wall (DW) into a distillation column is a well-known concept which can result in considerable energy savings for the separation of multicomponent mixtures. It is commonly known that heat streams across the DW, which are present due to temperature differences between both sides, may either increase or decrease the energy demand for a certain separation task. However, no work has been published so far which explains the maximum influence on energy demand. This article derives the maximum extent to which the minimum energy demand for a given column design can change due to heat transfer across the DW. Additionally, it is illustrated how energy-efficient column operation can be assured even if the total amount of transferred heat is unknown. These results show that the phenomenon of heat transfer across the DW can be handled very well with a suitable control strategy.Within this work, an EQ model based on the well-known MESH equations is used. 24 For the solution of the model equations, the software Aspen Custom Modeler (ACM) by Aspen Technology, is applied. ACM is an equation-oriented simulation tool and is thus especially suited for the Figure 2. Material streams being used in Eqs. 1 and 2.

The reactive dividing-wall column (RDWC) is an example of extensive process integration. Recently, an energy saving potential of 23 % for the RDWC for an exemplary reaction system has been reported. However, little is known so far whether this magnitude represents a typical value and how the reaction system properties affect the energy saving of the RDWC. Clearly, a prerequisite for the industrial application of this apparatus is a profound understanding of the process and a quick assessment of the energy saving at an early stage of process synthesis. Therefore, the influence of separation properties of the reaction system on the energy saving potential is systematically investigated. Also, the saving mechanisms are analyzed and how they are affected. Heuristics are presented which can be applied easily during the industrial process synthesis.

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