Lab-scaled performance evaluation of novel water-lean solvents for post combustion CO₂ capture  

This work focuses on demonstrating the energetic performance and operational reliability in a continuous system of RTI’s water-lean solvents for post-combustion CO₂ capture applications. RTI’s Non-Aqueous Solvent, NAS-1A was subjected to 100 hours of continuous, CO₂ capture and regeneration operation using a Lab-scale Gas Absorption System while the CO₂ capture efficiency, mass balance, and total energy inputs were monitored. Throughout the test period, NAS-1A demonstrated stable operation with 90% CO₂ capture while requiring about 15% lower total energy input for solvent regeneration compared to 30 wt% monoethanolamine solution. The use of a slipstream of CO₂-rich solvent from the absorber sump reduced the regenerated CO2 temperature before the gas was further cooled by the overhead condenser at the top of the desorber. The rich-split setup combined with a wash section may be an effective approach to remove water and solvent vapor from the regenerated CO₂ as well as to recover heat at the top of the desorber. NAS-1B was later developed and included a modifier component that lowers the heat of CO₂ absorption and reduces the vapor pressure of the amine component. The total energy inputs for 90% CO₂ capture with NAS-1B was found to be 25% less than that of the MEA. A gas chromatograph was used to monitor the amine concentration in the gas leaving the absorber wash section. It was found that under similar operating conditions, the presence of the modifier in NAS-1B reduces the amine in the absorber off-gas from 143 ppm in NAS-1A to 20 ppm.