The reactivity of several calcareous sorbents to SO/sub 2/ absorption is assessed in a laboratory-scale reactor under conditions representative of those encountered in the radiant zones of pulverized-coal-fired utility boilers. Rate of calcination, surface area development, regeneration of gas-phase sulfur species, and SO/sub 2/ capture ability are examined as a function of gas-phase environment and sorbent type. The sulfation reaction was experimentally decoupled from the calcination process, and over 50% conversion of calcium to sulfate was observed for one sorbent in 0.6 s. Sorbent reactivity to SO/sub 2/ is principally governed by specific surface area of the calcined sorbent, although sorbent type is a secondary influence. Peak sorbent temperature during calcination is the dominant factor governing surface area development for a given sorbent. The results demonstrate that (1) sorbent injection into the combustion zone (T > 1200 /sup 0/C) for SO/sub 2/ control is not optimal, and (2) a significant increase in sorbent reactivity will be attained by calcination at temperatures below 1200 /sup 0/C, the lowest value assessed in the present experiment.
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