Estimation of the Number of Distillation Sequences with Dividing Wall Column for Multi-component Separation

As an important separation unit, distillation column is widely applied in petrochemical and other process industry. For separating multicomponent mixtures, distillation is conducted sequentially in industry. Both individual column and distillation sequence optimization are efficient ways for saving energy consumption. Distillation sequence is usually evaluated by number of distillation subproblems, subgroups and distillation sequences. Distillation sequence has been well studied based on simple column assumption. Dividing wall column (DWC), which is an atypical distillation column for separating a multicomponent feed mixture into three output streams, as a thermally coupled distillation column, has been proposed and applied in distillation sequence. Usually sharp split is also assumed in most literatures on DWCs. A distillation sequence with DWC will give more number of feasible sequences. It is important to estimate the total available number of distillation sequences theoretically. In this work, distillation sequences with both simple column and DWC are considered. Inferential deduction method has been used to explore the number of distillation sequences for multi-component sharp splits. The three general term formulas are obtained with the assumption of sharp split. Under different assumptions, the corresponding numbers of distillation sequences are also discussed.