(520b) Optimizing Dividing Wall Distillation Columns

Colton Andrews, Bailee Roach, Bruce Eldridge

James R. Fair Process Science and Technology Center

The University of Texas at Austin

A dividing wall distillation column (DWC) is an energy efficient configuration capable of producing a high purity tertiary separation within a single column. A DWC includes additional degrees of freedom, making modeling and optimization more complex than standard distillation columns. This presentation covers the application of a rigorous simulation and optimization approach to DWC studies reported in the open literature.

Three DWC column configurations (one four-product DWC and two three-product DWCs) were reconstructed using a process simulator. Each cases was optimized using multivariable optimization software that can tests hundreds of design parameters. From a base case, the optimization software varied the DWC design parameters (number of stages, feed location, reboiler duty, etc.) across a specified range. Using the SHERPA optimization method, the objective function of the optimization software was set to minimize/maximize the key process parameters used to design a DWC. For example, the product stream purities were maximized whereas the reboiler duty was minimized. From the simulations, the “best” design was determined and a scale-up for each optimized design was conducted.

The optimization software in combination with the process simulator forms a powerful and efficient tool for the optimization of DWC simulations and designs. The enhanced efficiency and ease of use allows for many opportunities to test the various complicated design characteristics of the DWC. In the future, as more simulations and optimizations are performed using the optimization software in conjunction with the process simulator technique, the trends in design and operation of a DWC can be studied and, ultimately, a wider acceptance and understanding of the DWC can be achieved.