Robust and optimal energy-efficient distillation columns sequence

Abstract

This thesis presents an integrated and simultaneous solution framework for obtaining a robust energy-efficient distillation columns sequence. Several methods for robust energy-efficient distillation columns sequence synthesis have been developed. The aim was to provide a distillation column sequence design with a reasonable energy consumption when exposed to disturbances. However, the capability of a robust energy-efficient distillation columns sequence in maintaining its energy changes at a minimum with respect to feed conditions has not been analyzed. As a result, the operability of a designed energy-efficient distillation columns sequence may be questionable. There is a clear need to develop a new integrated and simultaneous solution framework for designing a robust energy-efficient distillation columns sequence. Therefore, the objective of this study was to develop a new integrated and simultaneous solution framework for an energy-efficient distillation columns sequence by considering process sensitivity and economic analyses. In Stage 1, an existing sequence was simulated using Aspen HYSYS process simulator to obtain design variables. In Stage 2, the design of the distillation column sequence was considered through rigorous design at different design variables. In Stage 3, the process sensitivity of each design was analyzed and compared, where the feed conditions and reflux ratios were changed for each design, which represented different column designs. The economic and robustness analyses for the sequence were performed in Stage 4. The capability of the proposed methodology was tested using a case study to obtain a robust energy-efficient distillation columns sequence. A maximum energy saving of separation was obtained with return of investment and payback period about 796 % and 0.13 year respectively. All of these findings proved that the proposed framework is capable of solving problems in the energy-efficient distillation columns sequence for obtaining a robust energy-efficient distillation columns sequence in an easy, efficient, and systematic manner.