Predicting Multiple Steady States in Equilibrium Reactive Distillation. 2. Analysis of Hybrid Systems

Guttinger and Morari (Ind. Eng. Chem. Res. 1998, 38, 1633−1648) developed graphical methods for the prediction of output multiplicities caused by the reactive vapor−liquid equilibrium in reactive distillation. These methods rest upon the limiting case of reactive columns of infinite length operated at infinite internal flows (∞/∞ analysis) and are directly applicable to systems where the reactions take place in the entire column (“nonhybrid” columns). In this work, the reactive ∞/∞ analysis is extended to columns with a reactive core (“hybrid” columns) by introduction of two new procedures. First, necessary and sufficient feasibility conditions for hybrid column profiles are derived under the assumption that each of the reactive and nonreactive column sections has infinite length. Using these conditions, an “exact” method is formulated where all possible products of such an ∞/∞ hybrid column can be located in the composition space (by a continuation of solutions). The existence of multiple steady states a...