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Reactive residue curve maps (RRCMs) are useful for the design of reactive distillation columns as a tool to establish feasible zones of reaction−separation. However, the calculation of an RRCM usually involves great computational effort due to the nonlinearity of the model equations and its iterative nature for the determination of reactive phase equilibrium. In this study, a simplified method for the generation of RRCMs is presented. This method is based on the application of reaction-invariant composition variables and assumes that the phase equilibrium constants (i.e., the relative volatilities) are independent of the temperature. Specifically, the phase equilibrium constants are calculated using a suitable estimation of the bubble temperature obtained from pure-component boiling temperatures and the reaction-invariant composition of liquid phase. These assumptions avoid iterative phase equilibrium calculations for obtaining a good approximation of RRCMs. Several reactive systems are used to identify the capabilities and limitations of the proposed method.

The design of reactive distillation (RD) has received significant attention because of the technological and economic advantages obtained from the simultaneous occurrence of reaction and separation. Although the advantages of RD are well-documented in the literature, the commercial applications of RD are still limited because of the control and operation complexity of these separation systems and the need for improved software tools to reliably model and design RD columns. In this study, a robust short-cut method for the design of multicomponent reactive distillation is presented. This method is based on distillation lines and tray-by-tray calculations defined in terms of reaction-invariant composition variables. Our method provides the number of theoretical stages, the operating reflux ratio, the feed tray location, and the top or bottom flow. We use three case studies to demonstrate the effectiveness of the proposed strategy, namely, the reactive systems for the syntheses of ETBE and MTBE in the presence of inert components and of TAME without inert components. The results obtained with our strategy show good agreement with those obtained using the rigorous model of the commercial simulator AspenONE Aspen Plus.

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