2014 Volume 47 Issue 2 Pages 87-108
Distillation is a common energy-intensive process. Accordingly, it is the first process to be addressed to improve the energy efficiency over both the short- and long-term. Recent studies and industrial applications have proven that advanced process integration and process intensification techniques such as the use of a thermally coupled distillation sequence (TCDS) and a dividing wall column (DWC) require the lowest amount of energy for the separation of mixtures into pure product streams. This paper reviews some energy-efficient distillation technologies that can be used in a retrofit design. The research on and implementation of retrofits using a TCDS and DWC are reviewed. This report proposes coupled schemes as alternatives to using a Petlyuk column that do not have the classical problem of controlling the vapor transfer from one column to another and have not previously been proposed for retrofits. These schemes are expected to make significant contributions to improving the energy efficiency and mitigating CO2 emission in the retrofitting of distillation systems. The authors evaluated a solution for retrofitting azeotropic and extractive distillation systems. Various issues such as the constraints, techno-economic analysis, controllability, and operability are discussed briefly to provide more insight into the application of TCDS and DWC technologies in the retrofit.