Process Energy Optimization and Heat Recovery in Amine-Based CO₂ Removal from Natural Gas Streams

The substantial energy requirement associated with solvent regeneration remains one of the principal challenges limiting the efficiency and economic viability of amine-based carbon dioxide (CO₂) capture in natural gas processing systems. Although chemical absorption technologies are widely employed for industrial CO₂ removal, insufficient attention has been directed toward integrated heat recovery and energy optimization strategies tailored to region-specific gas compositions and operational conditions. This study addresses this gap by evaluating energy optimization and heat integration approaches for amine-based CO₂ capture systems using Aspen HYSYS simulation under operating conditions representative of Niger Delta natural gas streams. A steady-state absorber–stripper model was developed employing the Electrolyte Non-Random Two-Liquid (e-NRTL) thermodynamic model to simulate CO₂ absorption using Monoethanolamine (MEA), Diethanolamine (DEA), and Methyldiethanolamine (MDEA) solvents. Key process performance indicators, including reboiler duty, condenser duty, heat exchanger performance, and specific energy consumption, were analyzed under varying operating parameters such as absorber pressure, temperature, solvent circulation rate, and inlet CO₂ concentration. In addition, heat integration strategies involving lean–rich heat exchanger optimization and thermal energy recovery configurations were systematically investigated to reduce regeneration energy demand. The results showed that regeneration energy requirements followed the order MEA > DEA > MDEA, with MEA exhibiting the highest reboiler duty because of stronger carbamate formation tendencies. Optimized heat integration reduced total process energy consumption by approximately 25–35%, with MDEA-based systems demonstrating the greatest thermal efficiency gains due to favorable solvent thermodynamics. Sensitivity analysis further identified absorber temperature and solvent circulation rate as the dominant factors influencing energy demand, while efficient lean–rich heat exchange significantly improved process thermal performance. However, the analysis also revealed important trade-offs between CO₂ capture efficiency and energy minimization, emphasizing the necessity for balanced process optimization. Overall, the study demonstrates that strategic heat integration combined with optimized operating conditions can substantially reduce the energy penalty associated with amine-based CO₂ capture processes. From an industrial standpoint, MDEA systems integrated with advanced heat recovery configurations provide the most energy-efficient option for large-scale natural gas treatment applications. These findings offer practical guidance for enhancing process efficiency, lowering operational costs, and supporting sustainable natural gas utilization in emerging hydrocarbon-producing regions.