Combustion effects and emission characteristics of SO2, CO, NO x and heavy metals during co-combustion of coal and dewatered sludge

The influences of dewatered sludge blending ratio in coal on flammability index (C) and combustion characteristic index (S) and release of sulfur dioxide (SO2), nitrogen oxide (NO (x) ), carbon monoxide (CO) and heavy metals (Hg, As, Cd, Pb and Cr) were studied. The impact on combustion characteristics could be ignored if less than 20% of dewatered sludge was added in coal. Besides, emission pattern experiments of NO (x) , SO2, CO and heavy metals were carried out in a high-temperature tubular furnace. Results showed that the conversion rate of NO (x) and total emission of SO2 reduced with the increase of sludge adding ratio, and a better effect of fixing sulfur could be obtained when the blending ratio reached 30%. Concentrations and distributions of five types of heavy metals in different residues (bottom ash and fly ash) as well as in flue gas were analyzed. It was shown that the characteristics of coal and sludge, as well as the volatilization of heavy metals had a great influence on the distribution of heavy metals.