Predicting multiple steady states in equilibrium reactive distillation. 1.Analysis of nonhybrid systems

During the last few years, multiple steady states (output multiplicities) h ave been discovered for reactive distillation processes, for example, for t he production of fuel ethers and for some esterification processes. Using t he transformation of Ung and Doherty (Chem. Eng. Sci. 1995e, 50 (1), 23-48) , a method is presented to predict the existence of output multiplicities b ased on the reactive vapor-liquid equilibrium for the limiting case of reac tive columns of infinite length operated at infinite internal flows. This g raphical method rests upon the infinity/infinity analysis for azeotropic di stillation columns by Bekiaris et al. (Ind. Eng. Chem. Res. 1993, 32 (9), 2 023-2038). It is directly applicable to systems where the reactions take pl ace in the entire column ("nonhybrid" columns). When all possible profiles and products are located through a bifurcation analysis, qualitative and qu antitative predictions are obtained. The region of feed compositions leadin g to multiple steady states can be constructed graphically by applying a ne cessary and sufficient geometrical condition. The prediction results are sh own to carry over to finite columns by application to the methyl tert-butyl ether process and are verified by simulation.