The effect of SO2 on fluidized bed calcium looping for CO2 capture

Attrition of a limestone during calcium looping cycles for CO2 capture was studied in a lab-scale fluidized bed apparatus with a focus on the effect of SO2 concentration in the flue gas. Batch experiments under alternating calcinationcarbonation conditions were carried out with different SO2 concentrations during the carbonation stage. Attrition processes were characterized by following the modifications of bed sorbent particle size distribution and the elutriation rates of fines throughout conversion over repeated cycles. Results show that relatively large attrition rates were experienced by the sorbent particles only during the first cycle. From the second cycle on the attrition rate progressively declines. The combined chemical-thermal treatment affects the particle structure making it increasingly hard. At the same time the CO2 capture capacity decays toward an asymptotic level, possibly related to the same structural modifications. The presence of SO2 in the flue gas appears to significantly influence the sorbent CO2 capacity, but not its attrition propensity.