Performance of hydration reactivated Ca looping sorbents in a pilot-scale, oxy-fired dual fluid bed unit

The progressive deactivation of CaO based sorbents is one of the major limitations of the Ca Looping cycle for postcombustion CO₂ capture. Techniques using the hydration of the spent CaO sorbent have been identified as a promising route for the reactivation of CaO sorbents but have so far not been tested at pilot scale using realistic calcination and carbonation conditions. In this work, the performance of sorbents reactivated by two different reactivation techniques (hydration-dehydration and superheating) was assessed in an oxy-fired, pilot-scale dual fluid bed unit. Compared to a spent sorbent, reactivated materials exhibited a ≈60% increase in CO₂ carrying capacity over 3 h of circulation as well as an increase in the sorbent attrition rate of 25% (superheating) and 50% (hydration-dehydration). In both cases, however, increased attrition did not lead to serious disruptions of system operation. A comparison of sorbent performance at laboratory and pilot scale suggested that high velocity impacts in the transfer lines were the main cause of attrition.