Christian Redepenning

Systematic and Optimization-Based Design of Integrated Reaction-Separation Processes

Abstract The conceptual design of chemical processes is a challenging task. Although systematic methods for process design have been developed in the last 25 years, only a few contributions address the simultaneous design and optimization of integrated reaction and separation processes. In this paper, we present a systematic and optimization-based approach to the design of such processes. Shortcut methods are utilized to screen alternative flowsheet structures. For the most promising alternatives a rigorous optimization of the entire flowsheet is consequently executed to determine the best alternative. The whole process design framework constitutes a procedure of incremental refinement and successive initialization and thus allows for the systematic generation and evaluation of reaction-separation processes. Consequently, it helps to shorten the time for developing new and innovative processes. In this work the methodology is illustrated by means of the case study of ethyl tert-butyl ether production.

Shortcut method for the design of extraction columns for multi-component mixture separations

Abstract Shortcut methods are valuable tools for the fast evaluation of different units and flowsheets in separation process design. In this paper, a systematic method for the estimation of the minimum solvent flow rate required in counter-current extraction columns is presented. A key element is the identification of a mode of operation under saddle-pinch control, characterizing multi-component extractive separations. The criterion defining this mode leads to a new shortcut method, which provides both, a systematic calculation of all pinch points and a criterion for minimum solvent flow rate estimation. It requires low computational effort, it is robust and does not need any specific initialization. Furthermore, the shortcut method is fully algorithmic and thus, at least in principle, applicable to any number of components. Its features are highlighted by means of an example of an extractive separation of a four component mixture.