Dividing Wall Columns (DWCs) allow the separation of a ternary mixture in one column shell by applying a vertical partition wall, yielding a reduction of operational and capital costs of up to 30%. Multiple DWC (mDWC), the consequent advancement of standard DWC, makes use of more than one partitioning wall, allowing the separation of quaternary or even higher mixtures in one column shell accompanied by a further reduction of energy consumption. Since no dedicated models for these columns are available in commercial process simulators, thermodynamic consistent flowsheets have to be designed and implemented. The thermally fully coupled Petlyuk arrangement is one important example. However, the initial convergence of these substituting flowsheets is demanding, since a large number of meaningful initial guesses have to be provided. A promising method for generating these first estimates are minimum vapor (V min ) diagrams. All internal flows can be extracted from these diagrams and used for robust initialization of the simulation. The goal of this work is to present the V min method in a comprehensive way in order to initialize mDWC simulations to predict the separation of four component mixtures. Additionally, the adaptation of the diagram to configurations different than Petlyuk arrangements for mDWC is evaluated and a systematic procedure to obtain them is presented. In the end, an example of a converging simulation is given, which was obtained with the values from the V min diagram.

This contribution elaborates the design considerations of a simplified version of a four-product multiple dividing wall column in pilot plant scale that will be built at Ulm University. This will be the first realization of a multiple dividing wall column worldwide. A detailed simulation approach, starting from the initialization by Vmin-method, is presented to obtain a feasible design of the column, taking into account the constraints of the operation within a university environment. The operating point was found by simulation studies, using the integrated optimization tool of AspenPlus© V10. It is shown that an NQ-curve can be applied on simplified multiple dividing wall columns. Based on the determined operating point, the thermodynamic and the fluid dynamic design of the pilot plant are discussed in detail. It is shown that the designed column can be operated to obtain all products with a purity of at least 98 mol%.

No abstract

Dividing-wall columns are a well-known and proven technology to separate a ternary mixture into pure products with significant savings in capital and operational costs compared to standard two-column configurations. A consequent advancement are multiple dividing-wall columns, which allow the separation of multicomponent mixtures in one column shell. However, due to their high complexity, no practical realization has been reported yet. This paper briefly discusses the current state of the art followed by a detailed description of a robust initialization of rigorous flow sheet simulations based on V min diagrams. With the data from the simulation a multi-objective optimization can be performed. The knowledge from the simulations shall be used to build the first multiple dividing-wall column worldwide.

No abstract

There was an error in the original article [...]

In early project stages, often no simulation results are available for dividing‐wall columns. Hence, shortcut methods are used to estimate suitable vapor and liquid splits. In a previous paper, it was demonstrated that V · min diagrams are a suited tool to satisfy this need. However, it has turned out that it shows weaknesses for columns with finite or non‐optimal stages. This contribution closes that gap and presents an extended approach to derive suited initial guesses. For this purpose, the original V · min diagram is combined with a heuristic approach to calculate Pareto‐optimal column designs resulting in a stage‐adapted V · min diagram. A comparative study illustrates that the new approach is a powerful tool to generate reliable guesses for multiple dividing‐wall column simulations with finite stage numbers.

No abstract