HiGee technology is emerging as an alternative to conventional tray and packed towers for mass-transfer applications. To evaluate the process intensification (volume reduction) potential of the technology, a systematic design procedure is developed in this work. HiGee designs using split packing innovation of Chandra et al. [Ind. Eng. Chem. Res. 2005, 44, 4051-4060] are developed for four industrially relevant distillation and absorption systems. Comparison with conventional packed or tray tower designs shows that significant volume reduction is possible. For the systems studied, the process intensification achieved is particularly impressive when the gas side mass-transfer resistance is dominant. The results suggest that split packing design innovation may be particularly suitable for intensification of gas side mass-transfer resistance controlled processes.
The flooding and mass transfer characteristics of a rotating packed bed (RPB) incorporating the split packing design innovation is studied. The air-water system is used for characterizing the flooding behavior, while mass transfer is studied for the chemisorption of CO 2 in aqueous NaOH. Danckwert's chemical method is used to infer the effective specific interfacial area (a e ) for mass transfer. The variation in the liquid side volumetric mass transfer coefficient (k L a e ) with operating conditions is also measured. Consistently higher values of a e and k L a e are observed for counter-rotation of the adjacent packing rings compared to co-rotation. The flooding and mass transfer results are compared with existing literature data on packed columns and conventional HiGee to evaluate the process intensification potential of the novel HiGee. The flooding limits are comparable to conventional HiGee, while the reported a e and k L a e values are higher.
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 compositionbased 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.
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