Attrition and impact fragmentation of limestones for SO2 capture in fluidized bed combustors

In this work an experimental program was set up with the following goals: i) assessing the extent of primary fragmentation of limestones upon calcination in the FB; ii) assessing the extent of attrition and secondary fragmentation upon sulfation of the sorbent under lowvelocity simulated combustion conditions in the FB; iii) assessing the extent of impact fragmentation of the sulfated limestones upon high-velocity collisions: experimental procedures were designed so as to simulate ex situ the conditions experienced by sorbent particles in a circulating FB as closely as possible; iv) characterizing the sorbents from the standpoint of their chemical and microstructural features and correlating fragmentation propensity with sorbent texture. Two high-calcium limestones (Limestone A and Limestone B) have been used in the experimental program. This work was triggered by the operational experience from industrialscale combustors suggesting that one of the limestones undergoes more extensive fragmentation than the other, in spite of the comparable degree of calcium utilization.