Comparative techno-economic analysis of CO₂ capture processes using blended amines

Blended amines synthesize the absorption characteristics of different amine solvents and show a great potential in carbon capture. However, a comprehensive techno-economic analysis (TEA) of the CO₂ absorption process using blended amines is still lacking. In this study, we investigated three blended amine solvents: MEA/MDEA, PZ/MEA, and PZ/MDEA, with commercially available amine MEA used as the benchmark. Rigorous process simulation and techno-economic analysis were applied to evaluate the performance of the carbon capture process in a steel plant. CO₂ molar loading in the lean solvent (α_lean) and stripper pressure (P) were optimized to minimize the total annualized cost (TAC). The results demonstrated that PZ/MDEA-based process is most cost-effective (31.43$/tCO₂) under the operating conditions of α_lean = 0.15 and P = 1.25 bar. The cost breakdown analysis revealed that α_lean and P significantly impact the TAC through the regeneration heat, equipment investment, and amines make-up cost. Furthermore, the energy analysis indicated that using a solvent with a low reaction enthalpy and heat capacity as well as high reactivity and absorption capacity could minimize the energy consumption of the process.