循环流化床锅炉汞排放和吸附实验研究

选取一台有代表性的440 t/h循环流化床锅炉，运用美国环保署推荐的安大略法，现场测定了入炉煤、底渣、飞灰和烟气中的各种汞形态浓度，获得了循环流化床锅炉汞排放特性。结果表明，循环流化床锅炉烟气中主要是颗粒汞，静电除尘装置的脱汞效率达98%，烟气汞排放浓度为0.062 mg/m3，底渣中汞小于总汞的1%。飞灰对汞强烈的吸附作用主要归因于其较高的含碳量，其次与飞灰中碳的结构形式和烟气温度有关。大幅度提高飞灰含碳量并不能提高其汞吸附量。

Experimental Study on Mercury Emission and Adsorption in Circulating Fluidized Bed Boiler

To evaluate the mercury emission from a circulating fluidized bed boiler, a representative 440 t/h circulating fluidized bed (CFB) utility boiler was selected to take the onsite measurement of mercury concentrations in feeding coal, bottom ash, fly ash and flue gas using the US EPA recommended Ontario Hydro method (OHM). The results show that particulate mercury is in the majority in flue gas of the CFB boiler. Mercury removal rate of the electrostatic precipitator (ESP) reaches 98%, mercury emission concentration in stack is only 0.062 mg/m3, and mercury content in bottom ash is less than 1%. It was found that the fly ashes were highly adsorptive to flue gas mercury because of its higher unburned carbon content. Adsorption effect is related to carbon pore structural properties of fly ash and temperature of flue gas. However mercury adsorption capacity by fly ash can't be improved any more when carbon content in fly ash increases further.