Customized Simulation – Optimized Separation during Distillation

DFG project: Modeling and Multi-objective Optimization of Multiple Dividing Wall Columns

In chemical process engineering, distillation is the most important thermal separation process and is responsible for around ten percent of Europe's energy requirements. It is therefore also a decisive lever for saving energy. This can be achieved, for example, by combining several processes in a single apparatus. 

Unfortunately, such apparatuses are often difficult to represent in conventional simulation software. In order to optimally design the processes and save energy, it is precisely these simulations that are needed. This is where our work comes in. Our researchers at Fraunhofer ITWM develop customized simulations and optimizations that represent exactly such processes robustly and efficiently. These help to show the potential in saving energy and costs for companies with the help of new technologies.

Multiple Dividing Wall Column of the University of Ulm
© Elvira Eberhardt / University of Ulm
The unique multiple partition column extends over three floors in the university's technical center.

One example are Dividing Wall Columns (DWC), in which several separation processes are combined in a single column. For several years, research has been carried out worldwide on dividing wall columns, including the Institute of Chemical Engineering at the University of Ulm. The university's pilot plant station now even houses the world's first Multiple Dividing Wall Column (MDWC), which extends the principle of the DWC to multiple dividing walls and to the separation of multiple substances. Together with researchers at the University of Ulm, we are developing customized simulations for simple and Multiple Dividing Wall Column.


Saving Energy Through Multi-Criteria Optimization

The widely used alternative for separating multi-substance mixtures is to connect several ordinary columns in series. In this case, one additional substance each is separated from the mixture step by step. The methods for multi-objective optimization developed at Fraunhofer ITWM show that there is a trade-off here. Although dividing wall columns have higher investment costs than conventional separation, they save energy and costs in operation. These energy savings for industrial companies can be in the range of 25 to 50 percent.  

Our researchers at Fraunhofer ITWM have also built up mathematical expertise on distillation processes over many years of working with companies in the chemical and pharmaceutical industries. They bring this knowledge in the optimization of processes and in the design of chemical production plants to the project team.

From Simulation to Distillation

Based on this research, our team successfully developed a novel way of modeling, simulating and optimizing (MSO) simple and multiple partition columns. Moreover, we demonstrate the scientific progress through various use cases and have already published the results in relevant papers. In a paper, we show that our solution is up to 1000 times faster than a solution using conventional simulation software.


Consider Uncertainties

For operation in practice, however, it is not sufficient to assume that the separation task is known exactly. Unknown variables have a major influence on optimal operation and must be taken into account in the design. Our researchers consider different uncertainties and develop strategies to best respond to them. On the one hand, this refers to operational uncertainties - such as fluctuating compositions – on the other hand, we have physical model parameters in mind as factors – for example, to describe thermodynamic equilibria.

Our model-based simulation and optimization of the process make it possible to quantify the savings potential and exploit it as fully as possible.

Schematic Representation of a Multiple Dividing Wall Column
© Fraunhofer ITWM
Schematic representation of a multiple dividing wall column for the separation of a four component mixture. The streams are split at the dividing walls and the resulting parallel streams do not mix with the column feed.
Researchers at the University of Ulm
© Elvira Eberhardt / University of Ulm
Researchers at Ulm University have commissioned a high-performance and, above all, sustainable distillation plant. The multiple dividing wall column, the only one of its kind in the world, handles as many chemical separation processes as three common distillation plants in industry.

Our Project Partner

Institute of Chemical Engineering at the University of Ulm (group around Prof. Dr.-Ing. Thomas Grützner)


Duration and Funding

The project is funded by the German Research Foundation (DFG) and is scheduled to run for four years.