模拟烟气中Hg排放形态的数值分析

Numerical Analysis of Mercury Emission Speciation in Simulated Flue Gas

为了深入研究燃煤Hg排放控制技术,在分析Hg形态转化过程及其影响因素基础上,通过控制变量法设定模拟烟气组分(HCl、O_2、NO、H_2O、CO_2和SO_2)的初始浓度值,利用化学动力学计算软件Chemkin进行数值模拟.结果表明:Cl原子的存在会促进单质Hg(Hg^0)向氧化态Hg转化,在一定范围内增加HCl的量有利于Hg的氧化;O_2会促进Hg的氧化但作用不如HCl明显;根据其所处的烟气气氛,NO既能促进Hg的氧化也能抑制Hg的氧化,在氧化性气氛中,NO的存在会提高Hg的氧化率;H_2O有利于Hg的氧化,而CO_2的存在会造成局部很强的还原性气氛,会抑制Hg的氧化;在不同条件下,SO_2可以促进或抑制Hg氧化.

Based on analysis of the transformation process of mercury speciation and related influencing factors, numerical simulations were conducted to study the control technology of coal-fired mercury emission with chemical kinetics calculation software Chemkin by setting the initial concentrations of various components （such as HCl, O2, NO, H2O, CO2 and SO2） in simulated flue gas using control variable method. Results show that the existence of chlorine atoms can promote the transformation of elemental mercury （Hg0） into oxidized mercury; increasing the amount of HCl within a certain range is beneficial to the oxidation of Hg0. O2 can promote the oxidation of mercury, but not as obvious as HCl. Depending on the flue gas atmosphere, NO can not only promote but also inhibit the oxidation of Hg0; in the oxide atmosphere, NO has a positive effect on the oxidation of Hg0. H2O is beneficial to the oxidation of mercury, while presence of CO2 would inhibt the oxidation of mercury due to the strong reducing atmosphere caused by CO2. Under different working conditions, SO2 can promote or inhibit the oxidation of Hg0.