污泥与煤在循环流化床混烧过程中的汞排放特性

在密相床截面积为0.23m×0.23m、高度为7 00m的循环流化床燃烧试验装置上进行了含汞污泥与煤的混烧试验.测试并分析讨论了污泥与煤混烧过程中汞的分布,探讨了Ca/S摩尔比、脱硫剂种类、过量空气系数等运行参数以及烟气成分对汞在烟气、飞灰和炉渣中形态分布的影响规律.结果表明,大部分汞进入烟气,且元素汞是混烧烟气中的主要存在形态.钙基脱硫剂对烟气中氧化态汞有较强的吸附脱除作用,CaO对汞的脱除效果要好于CaCO3.随着烟气中SO2、NOx浓度的增大,烟气中二价汞所占份额呈上升趋势.过量空气系数对烟气和灰渣中汞的浓度和形态分布有较大的影响.

Characteristics of mercury emission during co-combustion of sludge and coal in a circulating fluidized bed

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 NO_x 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.