(202d) Transesterification in the Reactive Dividing Wall Column – Energy Minimum Design and Operation

Process intensification has become an important concept to meet the challenges of an increasing global competition in the chemical industry. A promising possibility of process intensification is the integration of several primarily separated process operations into one single shell. Industrially applied examples are the reactive distillation or the dividing wall column. A further integration step leads to the highly integrated apparatus of the reactive dividing wall column (RDWC). The RDWC shows significant savings in investment as well as operational costs. Due to the high degree of integration and thus the resulting complexity, no industrial scale RDWC has been built and operated so far. Comprehensive studies on safe and reliable design methods as well as a steady operation are required to develop a profound process understanding for the complex apparatus of RDWC.

Our research aims to investigate the process of the RDWC holistically. As a promising application, a reaction system class of two reactants, which react reversibly to two products, is investigated. The products are the extreme boiling components of the reaction system, whereas the reactants are the middle boiling components. Additionally, a fifth inert component (intermediate boiling component) is present, which represents an impurity of the feed. This reaction system class is represented by the transesterification of hexyl acetate and butanol with the inert component heptanal. By the application of a systematic design method Pareto-optimal designs of the RDWC are developed and the robustness of the designs is investigated. From the results dependencies of the process parameters can be deduced and comprehensive process analysis can be carried out. Furthermore, the energy saving potential of RDWC compared to the process alternative of a reactive distillation sequence is determined. The operation of RDWC is investigated by dynamic simulations as well as experiments with a continuous RDWC pilot plant of 12 m height. Start-up strategies for a large number of operation points, steady-state operation and control strategies are investigated. From the results concepts for a safe operation of specified operating points and constant product purities during operation can be developed.

This oral presentation will show how to design and operate the reactive dividing wall column for a transesterification of butanol and hexyl acetate. First, the design method will be presented. Optimal process designs will be discussed in detail and dependencies of the process parameters will be pointed out. Additionally, pilot plant experimental results will be shown. Here, decisive factors for a steady and energy minimum operation will be discussed.