Sustainable Optimization of Quaternary Hydrocarbon Distillation: Heat Integration, Exergy Analysis and CO۲ Emission Evaluation

The growing demand for energy-efficient and environmentally sustainable separation technologies highlights the limitations of conventional distillation. This study examines the separation of a quaternary hydrocarbon mixture n-Butane, n-Hexane, n-Heptane, and n-Nonane using three consecutive distillation columns arranged in direct and indirect sequences. Several heat-integration strategies, including preheating, feed splitting, and multi-effect distillation, were applied individually and in hybrid combinations. Rigorous simulations were performed in Aspen HYSYS with the Peng–Robinson equation of state, and exergy and environmental assessments were conducted using custom MATLAB R۲۰۲۱b (The MathWorks, Inc.) codes. The results show that a hybrid configuration combining direct sequencing with feed splitting and multi-effect distillation delivers the best performance, reducing energy consumption by ۵۷.۲% (from ۳۱۳۴kW to ۱۳۴۲kW), increasing exergy efficiency to ۵۰.۵%, and decreasing CO₂ emissions by ۵۰.۷% (from ۶۷۰ to ۳۳۰kg/h). These findings highlight strong synergy between internal heat recovery and pressure-differential optimization. In contrast, some configurations, such as direct sequencing with feed splitting alone, produced higher energy use and lower efficiency due to thermal imbalance and excessive vapor loads.Overall, this study offers a robust methodological framework integrating process simulation, exergy-based optimization, and CO₂-emission evaluation, providing guidance for sustainably designing next-generation distillation systems in the chemical and petrochemical industries.

کلیدواژه ها:

Exergy analysis ، Energy consumption ، CO₂ emission ، heat integration ، Sustainable distillation design