Limestone SO sub 2 Reactivity and Causes for Reactivity Loss During Multi Cycle Utilization

摘要

The loss of limestone-SO sub 2 reactivity and capacity with increasing number of sulfation/regeneration cycles is caused by rapid limestone sintering (or possibly other internal structural changes) in the regenerator and not by a buildup of ash on the limestone surface. It is suggested that the presence of CaSO sub 4 in the limestone when exposed to the high temperature (1100 exp 0 C) accelerates limestone sintering, causing a decrease in total porosity and thus a decrease in SO sub 2 reactivity. Four experimental results lead to this conclusion: (1) the regenerated limestone lost porosity with each succeeding cycle; (2) electron microprobe analyses of tenth cycle sulfated material suggesting that sintering had occurred; (3) tenth cycle regenerated dolomite when crushed had the same SO sub 2 reactivity as uncrushed dolomite, indicating that the ash shell was not limiting the reaction rate; and (4) high temperature treatment of partially sulfated virgin limestone causes a loss of SO sub 2 reactivity. (ERA citation 03:034483)