Application of Aqueous Piperazine Solutions for CO2 Capture in a Waste-to-Energy Plant

The aim of this work is to assess the performance of piperazine-based aqueous solutions for the removal of CO2 from the flue gas of a waste-to-energy plant, for which no prior studies have been performed. Two solutions are considered, 8 m and 5 m piperazine. The chemical absorption process is simulated in Aspen Plus V.14, and the process configuration is optimized by performing subsequent sensitivity analyses on key design parameters, with the aim of minimizing the reboiler duty required for solvent regeneration. A preliminary economic assessment is also conducted. Comparison of the results indicates that operating with 8 m piperazine is more cost-effective than with 5 m piperazine, with a total annual cost difference of approximately 1.8 M$/y (about 15%). However, from a practical standpoint, a 5 m piperazine solution may be preferred because its larger solid-phase solubility range enables greater process flexibility while avoiding solid precipitation. Given the absence of an upper solubility limit for 5 m PZ (as suggested in the literature), operation at rich loadings above 0.80 mol-CO2/mol-PZ may be feasible, thereby reducing the thermal energy requirement for solvent regeneration.