(713c) Development of Fast and Thermally Stable Solvent System for CO2 Capture From Post-Combustion Flue Gas

Aqueous amine solutions have been identified as one of the most promising solvent systems for CO₂ capture from coal combustion. Despite the advantages of for example the well-known solvent system, such as aqueous monoethanolamine (MEA), the cost to capture CO₂ from coal combustion flue gas using such solvent system is expected to increase the electricity cost by 30% - 40%. The development of the novel solvent (CAER-S2) in the Center for Applied Energy Center at the University of Kentucky could largely reduce the operating and capital cost for CO₂ capture. The CAER-S2 solvent system has the advantages of fast CO₂ removal rate, high carbon cyclic loading, high thermal stability, low volatility, and commercial availability. Tests on both solvent screening apparatus and wetted-wall column at simulated scrubber condition indicate that the CO₂ removal rate of CAER-S2 solvent is more than 20% greater than 30 wt% MEA in the working carbon loading range. Such high removal rate helps reduce the absorber size. Vapor liquid equilibrium was also collected and discussed in terms of the working carbon loading range and heat of absorption. Thermal stability study performed at 125 °C and 135 °C shows that CAER-S2 can be operated at about 10 °C higher than that of 30 wt% MEA at given similar degradation rate. Operating at elevated temperature increases the CO₂ partial pressure at the top of stripper, lowering process energy by reducing the steam to CO₂ ratio and auxiliary energy for CO₂ compression.