Javad Ivakpour - Refining Division, Research Institute of Petroleum Industry, Tehran, Iran
Norolah Kasiri - Chemical Engineering Department, Iran University of Science & Technology

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 mixersfor considering possible bypass streams. The column specifications and bypass stream flow ratesare optimized by genetic algorithm based on rigorous simulation results. In the proposed methodeach component can be distributed in each column and no constraint is applied for componentrecovery 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.

Distillation, Sequencing, Optimization, Nonsharp Separation, Bypass