The CO2 capture performance of a high-intensity vortex spray scrubber

The present study focuses on the enhancement of CO2 capture efficiency using a high-intensity vortex spray scrubber by imparting swirl to the gas flow, which has the ability to augment the rates of heat and mass transfer. Experimental investigations into the reactive absorption of CO2 from a mixture of air–CO2 into an aqueous solution of NaOH in a laboratory-scale counter-current spray scrubber have been carried out. The mass transfer characteristics, in terms of the overall gas phase mass transfer coefficient (Kga) were investigated for both the swirling and the non-swirling (axial) gas flows through the scrubber in order to quantify the effect of swirl. The effects of the gas/liquid flow rates, flow arrangements, scrubber height and spray nozzle type on the CO2 capture performance were examined. For both the axial and the swirling flows, the Kga increases initially with increasing gas flow rate up to a certain limit, beyond which it becomes essentially constant, whereas the Kga increases continuously with the liquid flow rate within the measured range. The counter-current gas–droplets flow provides higher mass transfer rates compared with those in co-current flow. The Kga deceases with the increase in the tower height. The spray nozzle producing finer droplets provides enhanced mass transfer rates. It is found that imparting swirl in the gas flow enhances the Kga up to around 49% compared with that in axial flows.