Internal Heat Integration and Controllability of Double Feed Reactive Distillation Columns, 1. Effect of Feed Tray Location

• Published in: Industrial & engineering chemistry research 2008-10, Vol.47 (19), p.7294-7303
• Main Authors: Kumar, M. V. Pavan, Kaistha, N
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Distillation; Exact sciences and technology; Process Design and Control
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie071638n

The impact of altering feed tray locations (for the purpose of saving energy) on the controllability of double feed reactive distillation (RD) columns is evaluated for two case studies: a hypothetical ideal RD column and a methyl acetate RD column. Energy savings of 18.3% and 36.4% over the conventional design (feed immediately above and below the reactive zone) is achieved for the ideal and methyl acetate systems, respectively. A steady-state bifurcation analysis shows that, for both systems, output multiplicity, with respect to reboiler duty, occurs at a fixed reflux rate for the different designs (conventional/altered feed tray location). The output multiplicity is eliminated at a fixed reflux ratio. Closed-loop dynamic simulation results show that the controllability of the internally heat integrated ideal RD column deteriorates, compared to the conventional design. Unlike the conventional design, temperature-based inferential control is infeasible and composition-based control structures must be used. For the methyl acetate column, on the other hand, heat integration by altering the feed locations entails no loss in controllability using two-point temperature inferential control.