Energy-saving Design and Control for the Separation of Two Close-boiling Mixtures
Date Issued
2016
Date
2016
Author(s)
Huang, Wen-Chi
Abstract
Energy-saving process design and control for the separation of some close-boiling mixtures will be discussed in this thesis. There are two systems including ethylbenzene/styrene and cyclohexane/cyclohexene will be investigated. For the separation of ethylbenzene and styrene, several designs including conventional distillation, multi-effect distillation and internally heat-integrated distillation column (HIDiC) are considered to save energy cost and total annual cost. Conventional distillation will be the base case in order to be compared with other distillation systems. For multi-effect distillation, five alternative configurations which include Light-Split-Forward (LSF)、Light-Split-Reverse (LSR)、Heavy-Split-Forward (HSF)、Heavy-Split-Reverse (HSR) and Feed-Split (FS), are studied. The results show that FS configuration can decrease most energy cost, so the dynamic control structure of this configuration is also investigated. HIDiC design can save more energy than any kind of multi-effect distillations but the capital cost is also higher so that this design will be economic favorable if payback period can be extended or the energy cost is increased. For the separation of cyclohexane and cyclohexene, some energy-saving designs of extractive distillation system are studied. Compared with ethylbenzene and styrene, this mixtures is harder to be separated because there relative volatility is much lower. The result shows that extractive distillation with suitable entrainer can save great amont of energy cost. Further more, simple heat-integrated design can decrease more energy cost. Energy consumption can be further reduced when columns are operated under vacuum condition.
Subjects
close-boiling
multi-effect
HIDiC
extractive distillation
process design
process control
SDGs
Type
thesis
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