Investigation of high-reactivity calcium carbonate sorbent for enhanced SO2 capture

Kinetics of ultrafast, high-temperature sulfation is investigated for two calcium carbonates from different sources, a commercial calcium hydroxide and a laboratory-made modified hydrated lime powder. Time-resolved kinetic data are obtained for a 0-600 ms time scale at a temperature of 1080 degrees C with in-situ particle size classification. A mean particle size of 3.9 mu m is considered for sorbent comparison studies. It is observed that the high-surface-area Forsby carbonate exhibits extraordinarily high reactivity (50% in 500 ms) compared to other carbonate and hydrate powders. The difference in reactivity is most prominent in the short time scale of under 50 ms. Thorough investigations of the internal pore structure and surface area evolution in the initial 50 ms are conducted for both calcination and sulfation. The results elucidate the influence of internal pore structure in determining the initial reactivity and the final sorbent utilization.