CO2 capture enhancement in a fluidized bed of a modified Geldart C powder

In this work, we analyze the CO2 adsorption performance in a fluidized bed of a modified adsorbent, which is obtained by dry mixing a Ca(OH)2 fine cohesive powder (Geldart C) with a fluidizable silica nanopowder. The silica nanoparticle agglomerates serve as carriers of the adsorbent Ca(OH)2 fine particles, which are thus provided with a vehicle for improved fluidization. Experimental measurements are presented on the capture capacity of the modified adsorbent as compared to the original adsorbent. As the gas flow rate is increased, gas channeling in the fluidized bed of the original adsorbent causes a rapid decrease of the time for CO2 breakthrough in the effluent gas (BT) and the capture capacity at CO2 breakthrough (XBT). In contrast, because of the improvement of gas–solid contact efficiency, BT and XBT are appreciably increased for the modified adsorbent. Thus, even though the silica nanoparticle agglomerates do not contribute directly to CO2 adsorption, fluidization enhancement allows for maintaining relatively higher capture capacities at large values of the gas flow rate.

Fluidizable agglomerates of a nanostructured SiO2 powder serve as vehicle of CO2 sorbent Ca(OH)2 particles. The increase of the effective gas-solid contact surface in a fluidized bed gives rise to a significant enhancement of the CO2 capture efficiency as seen in the figure from the rate of increase of CO2 concentration in the effluent gas.Figure optionsDownload as PowerPoint slide