Design Considerations of a Simplified Multiple Dividing Wall Column Pilot Plant

Abstract

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%.

Shortcut Method for Initialization of Dividing Wall Columns and Estimating Pareto-Optimal NQ-curves

“…As a consequence, in the min V diagram the AB split is shifted, the new shifted peak is often denoted as AB', where the superscript prime generally indicates an adjustment of the min V diagram compared to the original one of the feed mixture. As long as the adjusted AB' split stays below the highest peak, the smDWC does not require more energy than the full mDWC [13]. A detailed publication about the calculation of the shifted peaks for such a column can be found elsewhere [10].…”

“…As quaternary mixture ethanol, n-propanol, i-butanol and n-butanol is considered, since it is suggested to be suited for the smDWC in literature [13]. The mixture is assumed to be equimolar and at liquid boiling state, the feed stream is set to 100 mol/h.…”

“…The mixture is assumed to be equimolar and at liquid boiling state, the feed stream is set to 100 mol/h. For the thermodynamic modelling the non-random two-liquid model (NRTL) is used and suitability of the parameters is validated with experimental data from literature [13]. The relative volatilities of the components are determined to be α = [4.7, 2.2, 1.5, 1.0].…”

“…For this purpose, an optimization-based empirical methodology is developed. Note that this contribution sets the focus on dividing wall columns with two dividing walls to split quaternary mixtures as presented in [13], nevertheless the procedure is adaptable to any other kind of distillation columns. This contribution is organized as follows.…”

Investigation of Control Structures for a Four‐Product Laboratory Multiple Dividing‐Wall Column Using Dynamic Simulation

“…Purities of at least 98 mol % of the main component in the respective product stream are set as constraints. The results obtained are the number of stages in each separation section, the values for the internal vapor-and liquid splits as well as the diameter of the column sections [16].…”