Fluidized bed calcium looping: the effect of SO2 on sorbent attrition and CO2 capture capacity

The CO2 capture capacity and the extent of particle attrition during simulated calcium looping cycles in a fluidized bed were studied, with a focus on the influence of SO2 in the flue gas. Five calcination/carbonation cycles (calcination at 850°C and 20% CO2, carbonation at 700°C and 16% CO2) were carried out with a reference limestone using different SO2 concentrations during carbonation (110 and 1800 ppm). Attrition phenomena were characterized by following the modifications of bed sorbent particle size distribution and the elutriation rates of fines throughout conversion over repeated cycles. Results showed that the CO2 capture capacity decreased with the cycles, as expected. The presence of SO2 had a detrimental effect, but the SO2 concentration affected the capacity less than anticipated. In-bed particle fragmentation was always limited, while the attrition rate decreased with the number of cycles, and was only moderately affected by the presence of SO2.