Intensified plant-scale post-combustion CO2 capture based on piperazine-activated methyldiethanolamine solution via cascaded stationary and rotating packed beds

Solvent-based post-combustion carbon capture (PCC) with packed beds (PBs) suffers from high energy consumption and large space occupation in the commercialization process. Benefiting from the strong separation efficiency, compact design and wide solvent adaptability of rotating packed beds (RPBs), replacing PBs with RPBs and integrating them with energy-saving solvents is a potential solution to enable complete commercialization of PCC. Nonetheless, the size constraints and economic uncertainties associated with RPBs remain key challenges hindering their large-scale implementation. Using RPBs in series/parallel or with PBs promises a balance between space savings and cost reduction, but this trade-off advantage has not yet been quantified. Therefore, this work provides a detailed energetic and economic analysis of a cascade combination of PB and RPB for industrial-scale PCC using methyldiethanolamine + piperazine (MDEA + PZ) aqueous solution. Rate-based models for PB and RPB were first developed and validated in Aspen Plus®, where the new correlations required for high gravity characteristics in RPB were written into Visual Fortran sub-routines and linked to Aspen Plus®. Three different absorption configurations (single PB, single RPB, or cascade of the two) were then proposed and implemented in Aspen Plus® for the PCC process with a practical-scale application targeting 10000 m³/h flue gas. The results show that using a cascade combination of PB and RPB to replace a single RPB can reduce the total specific capture energy from 5.19 GJ/tCO₂ to 4.30 GJ/tCO₂, and save up to 44.58 % of the capture cost over an electricity price range of $0.1–0.5/kWh.