Potential of Amine-based Solvents for Energy-saving CO₂ Capture from a Coal-fired Power Plant

Abstract

The potential of amine-based solvents was investigated by a thermodynamic analysis for low-energy CO₂ capture from the flue gas of a thermal power plant. The solubility of CO₂ into the amine-based solvent was predicted by the vapor-liquid equilibrium model on the basis of absorption reactions between CO₂ and amine. The model was covered for developed and developing amine-based solvents. Considering the energy consumptions of CO₂ capture and compression, the power output of the coal-fired power plant with a post-combustion CO₂ capture was estimated. The results showed that the solvent characteristics of high CO₂ cyclic capacity and low absorption heat had an important effect on reducing the thermal energy requirement for CO₂ capture. In the case of CO₂ capture from a 12% CO₂-containing flue gas, the lowest thermal energy requirement was estimated at approximately 2 GJ/t-CO₂, and the efficiency penalty of power generation was reduced to 7.2%pt. Also, concerning the impact of CO₂ capture and compression on the power generation system, 1%pt. of power generation efficiency could be recovered by lowering 0.6 GJ/t-CO₂ of the thermal energy requirement of CO₂ capture. These results mean that the aminebased solvents still have high capability to improve energy performance of post-combustion CO₂ capture. However, lowering the regeneration temperature in the range of 90 °C to 130 °C did not have a significant advantage in reducing energy consumption. This comprehensive analysis for the CO₂ capture and compression integrated with a coal-fired power plant is useful for process evaluation, and the desire will be to extend the analysis to other applications.