CO ₂ capture with modified lime-based pellet sorbents

Modified lime-based pellets were studied as potential regenerable high-temperature CO ₂ sorbents using calcium aluminate cement binders to enhance pellet strength. A mechanical pelletizer was employed for granulation of the powdered materials, specifically quick lime and hydrated lime, produced from Graymont limestone with the addition of spray water. The CO ₂ carrying capacity of both the pellet sorbents and the parent limestone was investigated over repeated calcination/carbonation cycles. The attrition resistance of these pellets was examined using a bubbling fluidized bed (50 mm ID). The particle size distribution of both the calcined pellets was determined before and after alternating calcination/carbonation cycles. The CO ₂ carrying capacity of pelletized sorbent was more stable over multiple cycles. Attrition tests showed that high-temperature fluidization did not result in significantly pronounced attrition for the pellet sorbents. This is an abstract of a paper presented at the 2012 AIChE Spring Meeting and 8th Global Congress on Process Safety (Houston, TX 4/1-5/2012).