CaO interactions in the staged combustion of coal

The interaction of CaO with pyrite, COS, H/sub 2/S, and SO/sub 2/ were examined under fuel-rich conditions to determine the role of CaS formation in the LIMB process. Rate calculations based on differential reactor kinetics suggest that CaS formation in the second or less available is low. Coal-burning experiments on the fuel-rich side using CaO-impregnated coals also show that CaS formation is minimal. The experimental studies suggest that sulfide-sulfate-sulfur dioxide equilibria deter the formation of CaS in the fuel-rich zones of LIMB, necessitating that CaO be added with the secondary or tertiary air for optimum removal of sulfur dioxide.