Robust optimization of the heteroextractive distillation column for the purification of water/acetic acid mixtures using p-xylene as entrainer

The separation of water and acetic acid mixtures is a challenging task in the terephthalic acid production process. This study addresses the techno-economical optimization of an heteroextractive distillation column that uses p-xylene as entrainer. The optimization of this column is performed by means of robust optimizers belonging to the BzzMath library, coupled with the detailed process simulation of the downstream section performed with the commercial software SimSci PRO/II. A comparison with respect to the commercial simulator optimizer and a quantification of benefits are given. Results show that the BzzMath robust optimizer reaches a lower Total Annual Cost (3.5%) with respect to the commercial software optimization. Finally, the comparison with other entrainers proposed in literature for the advanced distillation of the water/acetic acid mixtures demonstrates the economical and operational appeal of this process configuration. (C) 2016 Elsevier Ltd. All rights reserved.