Design and control analysis of the side-stream extractive distillation column with low concentration intermediate-boiling entrainer

Side-stream extractive distillation (SSED) column has attracted increasing attentions due to its simple structure for separating the binary azeotropes using intermediate-boiling entrainer. However, the high-concentration intermediate-boiling entrainer may lead to a disadvantage of high energy consump-tion. To address this issue, an improved design of the SSED column with low-concentration intermediate-boiling entrainer is proposed to improve economic performances without adversely affecting its control-lability for separating binary azeotropes. Economic optimization and sensitivity analysis are employed for designing SSED column using low-concentration intermediate-boiling entrainer for separating the methanol/toluene azeotrope, in which the advantages of cost reduction and energy saving have been observed. Following that, multiple case studies have been conducted to demonstrate the superiority of low-concentration intermediate-boiling entrainer in energy saving. Finally, dynamic control analysis illustrates that the SSED column using low-concentration intermediate-boiling entrainer can react effec-tively against the feed flowrates fluctuations and compositions disturbances by adopting control struc-tures with composition controller. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study proposes an improved design of the SSED column using low-concentration intermediate-boiling entrainer to enhance economic performance and achieve energy saving benefits in separating binary azeotropes. Economic optimization, sensitivity analysis, and multiple case studies have demonstrated the superiority of low-concentration intermediate-boiling entrainer in energy saving. Furthermore, dynamic control analysis shows that the SSED column using low-concentration intermediate-boiling entrainer can effectively respond to feed flowrate fluctuations and composition disturbances.