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

Energy savings using an internally heat-integrated distillation column (HIDiC) for the vacuum separation of acetic acid/ acetic anhydride was theoretically analyzed and compared to the simulation of an operating column at Eastman Chemical Company as well as a vapor recompression column using ASPEN Plus. In these simulations, the design and operating variables were defined and optimized to minimize total energy usage. 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 was also examined. These simulations showed that one HIDiC configuration had 62% energy savings over the traditional column configuration. The distillation column using vapor recompression was evaluated as a bench mark for comparison for the HIDiC configuration and the traditional column. Its vapor production was significantly higher than both other configurations, resulting in significantly increased energy usage.