Post-Combustion CO<sub>2</sub> Capture from an Industrial Power Plant Using Five Chemical Solvents: A Comparative TEA

CO<sub>2</sub> capture processes using five chemical solvents were modeled in Aspen Plus V.12.1 for the capture of over 90% CO<sub>2</sub> from a 456 ton/hour split flue gas stream containing 12.02 mol% CO<sub>2</sub> emitted by the Longview 780 MW power plant (West Virginia, USA). Since the flue gas contained 33.10 ppmv SO<sub>2</sub> and 35.47 ppmv NO<sub>2</sub>, a gas polishing process, using deionized water (DIW), was included in the model for complete scrubbing of SO<sub>2</sub> and NO<sub>2</sub> from the raw flue gas before the CO<sub>2</sub> capture process. The five chemicals used for CO<sub>2</sub> capture included three amine-based solvents (ABs) (monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), and (piperazine/methyldiethanolamine (PZ/MDEA)), and two amino acid-based solvents (AAs) (sodium glycinates (SGS) and potassium glycinates (PGS)). Since SGS and PGS exhibit phase separation, the CO<sub>2</sub> capture processes followed two distinct pathways: Pathway (i) involved direct CO<sub>2</sub> capture using all five solvents, and Pathway (ii) focused on bicarbonate nanomaterials production using only SGS and PGS. A Techno-economic assessment (TEA) of the CO<sub>2</sub> capture processes was conducted and the corresponding process hydraulics and mass transfer characteristics were calculated. The simulation results revealed the following: (1) for Pathway (i), the levelized cost of CO<sub>2</sub> capture (LCOC) for PGS was lower than that for SGS, MEA, AMP, and PZ/MDEA; (2) for Pathway (ii), PGS had a lower LCOC than SGS; (3) Pathway (ii) was more economically more favorable than Pathway (i); and (4) under the operating conditions used, the two-phase pressure drop values were negligible, and the liquid-side mass transfer coefficients (k<sub>L</sub>) were an order of magnitude smaller than gas-side mass transfer coefficients (k<sub>G</sub>), suggesting that the gas-liquid mass transfer resistance (1/k<sub>L</sub>) was in the liquid-side. Our techno-economic analysis (TEA) underscores the uniqueness of using AAs solvents in industrial CO<sub>2</sub> capture, offering significant cost savings through the production of valuable bicarbonate nanomaterials.