Comparison of Energy Usage for the Vacuum Separation of Acetic Acid/Acetic Anhydride Using an Internally Heat Integrated Distillation Column (HIDiC)

Abstract

Energy savings for an internally heat-integrated distillation column (HIDiC) and a vapor recompression column for the vacuum separation of acetic acid/acetic anhydride was theoretically analyzed and compared to the simulation of a reference column configuration of the Eastman Chemical Company using ASPEN Plus. In these simulations, the design and operating variables were defined and optimized to minimize total energy used. The effects of design variables such as quantity and location of the heat integration stages, reflux ratio, and rectifying section absolute pressure on energy consumption and product purity revealed that one HIDiC configuration had 62% energy savings over the reference column. The distillation column using vapor recompression was evaluated as a benchmark for comparing the HIDiC configurations and the reference column. The VRC column simulation predicted both increased product purity and an energy savings of 91% over the reference unit.

Keywords:

• Acetic acid
• acetic anhydride
• distillation
• HIDiC

ACKNOWLEDGEMENT

This investigation was partially supported by Eastman Chemical Company in Kingsport, TN and the Department of Chemical Engineering at the University of South Carolina in Columbia, SC.