Double vapor recompression strategy as a retrofit solution for the conventional benzene-toluene-xylene distillation

Abstract

The benzene-toluene-xylene (BTX) mixture stands out as one of the most important in the petrochemical industry. In an effort to improve operational conditions and enhance the sustainability of separation systems, new technologies are continuously developed. Thus, this study aims to evaluate the potential economic and environmental benefits of two optimal double vapor recompression schemes applied to the conventional BTX separation plant (DVR and DVRC), while contrasting the outcomes with two previous configurations proposed for the same system, which incorporate the divided-wall strategy, with (DWC-VR) and without (DWC) vapor recompression. The economic analysis shows that the DVRC configuration achieves the lowest total annual cost (TAC) at $12.98 million/year, followed by DVR ($13.09 million/year) and DWC-VR ($13.36 million/year). In terms of environmental performance, DVRC presents the lowest CO₂ emissions, offering an 8.6 % reduction over DWC-VR. However, DWC-VR leads to a greater reduction in water consumption, surpassing DVRC by approximately 34 %. These results suggest that DVRC may be a more suitable configuration for retrofitting existing, older plants worldwide, offering both cost and environmental benefits. On the other hand, DWC-VR can be considered as a more complex improvement and revamping alternative, particularly for new projects or advanced process upgrades.