Analysis of Divided-Wall Column for Extractive Distillation.

Abstract

The divided-wall column (thereinafter called DWC) has received widespread attention in terms of its compact structure and high thermal efficiency, which offers savings in capital and energy costs, since it was originally reported by Wright and Elizabeth in 1949. Some DWCs, have already been commercialized successfully including that of the authors in 1996. However, with the existing DWC construction, they cannot be applied to the separation of azeotropic systems or close boiling component systems, and the application has been limited to ordinary ternary systems. i. e. the separation of light, middle, and heavy fractions. In this paper, a new extractive distillation column that the concept of DWC can be applied to is shown, and a comparison with the conventional two-column sequence has been presented in terms of process compactness and heat intergration. The devised column here is called DWC-E, and it has the following features: 1) DWC-E is divided from the column top to the midportion between the feed plate and the bottom by a vertical wall (splitting plate), and 2) DWC-E is compact-type process with only two top condensers and one reboiler. Moreover, a simulation of acetone-methanol-water extractive distillation is carried out to examine the validity of DT DWC-E. The result shows that DWC-E can save a maximum of 36% energy consumption compared to the conventional two-column sequence.