A Comparative Study of Mea and Piperazine-Promoted K₂C₂O₃ for Post-Combustion of CO₂ Capture and an Economic Evaluation of a Coal-Fired Power Plant with Absorption-Based CO₂ Capture by PZ-K₂CO₃
Author : Castillo, Patricia Andrie M.
Major Adviser : Alcantara, Jerico Z.
Committee Members : Gatdula, Kristel M.; Bataller, Butch G.
Year : 2021
Month : June
Type : Thesis
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Factors that have a significant impact on retrofitting a coal-fired power plant with an absorption-based post-combustion CO₂ capture were discussed. These factors include solvent concentration, solvent pH, gas flow rate, liquid flow rate, CO₂ partial pressure, and reaction temperature. The solvent performances of monoethanolamine (MEA) and piperazine-promoted potassium carbonate (PZ-K₂CO₃) were also compared and evaluated based on different, relevant solvent parameters such as CO₂ loading, cyclic capacity, CO₂ removal efficiency, absorption rate, and heat of absorption. Preliminary analyses of these two solvents based on literature revealed that PZ- K₂CO₃ performed better than MEA in the experimental scale and pilot campaigns. Compared to MEA, PZ-K₂CO₃ has a higher CO₂ loading, faster absorption rate, less heat of regeneration required, and experiences less solvent loss due to its lower volatility and resistance to thermal and oxidative degradation. Upon the economic evaluation of a 600 MWe coal-fired power plant retrofitted with a CO₂ capture absorption system by 2.5-m PZ and 2.5-m K₂CO₃, it was found that the process is not feasible. The computed return on investment (ROI) for this model was 2.83%, with an MAR of 16%. While the payback period (PBP) was 29.45 years for a 25-year operation. The 30 wt% MEA base case had an ROI of 8.05%, which is greater than its MAR of 8%, and a payback period of 10.35 years, making the CO₂-MEA-H₂O process more cost- efficient. The net power loss for PZ- K₂CO₃ was lower at 17.11%, while the 30 wt% MEA base case experienced a 23.33% power loss.
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