Integration of Dividing Wall Columns with Middle Vessels for Batch Distillation under Total Reflux: Modeling and Optimization

Dividing wall columns, one of the thermally coupled distillation technologies, are widely used in the continuous separation process due to their energy-saving advantages because multiple middle-vessel columns are an important improvement over traditional batch distillation (TBD). To save energy requirement and time consumption further for batch distillation, a novel batch distillation configuration was proposed: the middle vessel-coupled dividing wall distillation column, which is different from the other two configurations of TBD, and multiple middle-vessel batch distillation. Detailed modeling and optimization of the above three configurations were conducted using a particle swarm algorithm, where the quaternary mixture of n-pentane (C5), n-hexane (C6), n-heptane (C7), and n-octane (C8) was used as a case. The results show that the separation time of the multiple middle-vessel column was the shortest when the purity requirement was not high, while the separation capacity of the new configuration was the best under the same conditions and no intermediate cuts were produced. Finally, the operation strategy of the new configuration was improved by adding fresh feed in the tank of the column top.