The prediction of mercury retention in ash from pulverised combustion of coal and sewage sludge

Coal-fired utility boilers and waste incinerators are the principal anthropogenic sources of atmospheric mercury. In order to provide a greater understanding of the behaviour of mercury in and downstream of a combustor, a novel mathematical model has been developed to predict mercury vaporisation and partitioning. The model has been validated in a 0.5 MW furnace, fired with pulverised coal and a coal/dried sewage sludge blend. Flue gas fly ash was sampled to ascertain the removal of mercury through fly ash adsorption and condensation at low flue gas temperatures (ca. 333 K). Mercury vaporisation, speciation, adsorbence and ash enrichment have been successfully predicted.