Reactivation of sorbents for calcium looping application by steam hydration

This paper reports on the preliminary findings obtained by applying the steam-hydration technique to a spent German sorbent coming from a FB calcium looping process. The attention was focused on the regeneration of the sorbent CO2 capture capacity induced by steam hydration, and on the effect that this technique has on the attrition tendency of the reactivated material. To this end, calcium looping (before and after steam hydration) and steam-hydration tests were carried out in a lab-scale FB reactor. In particular, steam hydration of the spent sorbent was performed at 250°C for 10 min in a 50% steam-containing atmosphere. With reference to calcium looping tests, the rate of fines generation, the sorbent particle size distribution and the CO2 capture capacity were monitored. Results highlighted the effectiveness of the steam-hydration treatment in reactivating the sorbent activity to CO2 capture, and that steam hydration brought about only a very slight increase in the sorbent attrition tendency. Results were also compared with those obtained (and previously published) under the same calcium looping operating conditions and with the same sorbent, but reactivated by liquid water hydration at 25°C for 10 min.