Pilot Plant Study of An Amine-Carbonate Solvent Blend for Post-Combustion CO2 Capture

Chemical absorption with solvents continues to be explored as a viable process option for post-combustion CO₂ capture in coal-fired power plants. Alkanolamines are widely used for the absorption of CO₂ and particularly, monoethanolamine (MEA) is considered an industrial benchmark for power plant post-combustion capture. However, the energy requirement for CO₂ capture using MEA in utility flue gas application is estimated to reduce a coal-fired power plant’s output by about 30% with a concomitant increase in the cost of electricity. Alternative solvents have therefore garnered major research consideration to lower the parasitic energy losses and associated costs in using chemical absorption for CO₂ capture in coal-fired power plants.

In this study, the performance of an amine-carbonate solvent blend was examined in a 0.1MWth pilot plant using coal derived flue gas. Experiments were carried out under similar conditions for comparison with standard 30 wt% MEA. The comparison was done by evaluating the capture efficiency for CO₂ absorption, the overall mass transfer, and the energy penalty. The parameters varied during the experiments were the solvent lean loading and the liquid to gas (L/G) ratio. It was demonstrated that the blend resulted in a richer carbon loaded solution in the absorber compared to MEA. The resultant energy penalty for regeneration was estimated to be about 10% lower for the solvent blend. Additionally, the factors contributing to the observed trends will be discussed.