Optimum Sequence of Non-Sharp Distillation Columns for Ternary Separation

The optimization of distillation column sequences for nonsharp separation of ternary mixture is studied. The four possible basic sequences are compared based on the cost functions. Each sequence contains one or two distillation columns and an adequate number of splitters and mixers for considering possible bypass streams. The column specifications and bypass stream flow rates are optimized by genetic algorithm based on rigorous simulation results. In the proposed method each component can be distributed in each column and no constraint is applied for component recovery fraction. Implementation of the proposed method for three examples shows that nonsharp separators with distributed components and complex column arrangements can frequently reduce the separation costs up to 77% compared to the optimum sequence with sharp separators.