Sustainability analysis and retrofitting of energy efficient distillation columns sequence

Abstract

Distillation continues to be the most important separation technique in the chemical process industry. Recently, a new energy efficient distillation columns sequence methodology that is able to improve the energy efficiency of the existing separation systems without having major modifications has been developed. However, the developed methodology only considered the energy savings without taking into consideration the sustainability criteria. Therefore, the aim of this study was to extend the energy efficient distillation column sequence methodology by taking into account the sustainability analysis as well as the retrofitting analysis in designing sustainable sequence for distillation columns system in an easier, efficient, and systematic way. Accordingly, the methodology was divided into four hierarchical stages. The analysis of energy consumption in distillation columns sequences was simulated within Aspen HYSYS simulation environment while the sustainability index was analysed using a developed Excel-based sustainability evaluator. The capability of the proposed methodology in designing sustainable and retrofit energy efficient distillation columns sequence was tested using Aromatic Mixtures (AM) separation process, Hydrocarbon Mixtures (HM) separation process, and Natural Gas Liquids (NGLs) separation process. The results obtained shown that the proposed methodology is able to reduce energy consumption to 12 % as well as 13 % reduction in overall sustainability index for the AM separation process. Besides that, 38 % of energy reduction and 32 % of the overall sustainability index reduction was achieved in overall for HM case studies. Furthermore, overall NGLs case study shows a reduction in energy consumption up to 21 % as well as 22 % of overall sustainability index. Thus, the developed methodology is capable of operating the separation process with less energy requirement and also gives better sustainability performance in an easy, practical, and systematic manner.