Characteristics of mercury emission during co-combustion of sludge and coal in a circulating fluidized bed
污泥与煤在循环流化床混烧过程中的汞排放特性

An experimental study on co-combustion of sludge and coal was conducted in a circulating fluidized bed furnace having a dense bed cross section of 0.23 m×0.23 m and height of 7 m. The speciation distribution of emitted mercury was measured and is discussed. The effects of major operational parameters such as Ca/Smolar ratio, desulfurization sorbents and excess air coefficient and flue gas components on the speciation distribution of mercury in flue gas, fly ash and slag during the co-combustion process were investigated. The results indicate that the majority of mercury goes into flue gas in which elemental mercury is the major species. Calcium-based sorbents can adsorb Hg2+ in flue gas effectively, and CaO can adsorb more mercury than CaCO3. The content of Hg2+ in flue gas increases with the concentrations of SO2 and NOx in flue gas. The excess air coefficient was found to greatly influence mercury concentration and its speciation both in flue gas and in fly ash and slag.