INORGANIC AEROSOLS AND THEIR ROLE IN CATALYZING SULFURIC-ACID PRODUCTION IN FURNACES

Submicrometer ash and sulfur oxides are important pollutants formed du ring pulverized coal combustion. The submicrometer ash contains known catalysts for sulfur dioxide oxidation as well as alkaline species tha t will react with sulfur oxides. This work was an investigation to det ermine if submicrometer ash-sulfur oxide interactions can have a signi ficant impact on the fate of sulfur. The submicrometer-ash-sulfur oxid e interaction studies were carried out using submicrometer ash of cont rolled composition generated from the combustion of synthetic chars. T he submicrometer ash was either exposed to SO2 in the combustion chamb er or immobilized on a quartz-fiber filter for later exposure to SO2.S ubmicrometer-ash catalysis of SO2 oxidation was found to contribute si gnificantly to the SO3 formed in the convective passes of a utility bo iler, depending on the coal, combustion conditions, and temperature pr ofile in the convective section. The calcium within the freshly formed submicrometer ash appears to sulfate more rapidly than would be predi cted from rates published in the literature and is expected to sulfate completely in the convective section of a utility boiler.