添加剂在生物质燃料燃烧时对NO排放的影响

Characteristics of the NO Emissions Controlled by Nano Ironbased Additives During Biomass Combustion and Its Mechanism

为控制生物质燃烧过程中NOx的排放,本研究采用向生物质中添加纳米铁基添加剂的方式进行NO燃烧抑制研究。在一维管式炉中,分别对含有纳米Fe2O3添加剂的三种典型生物质燃料玉米秸秆、稻壳和锯末进行生物质取样100 mg,在700、800和900℃工况下实验研究NO排放特性。结果表明：Fe2O3可以有效地降低NO的峰值。随着温度升高,玉米秸秆和锯末的NO峰值降低率加大,在800℃时稻壳的NO峰值降低率最大。不同温度下,添加1 mg的Fe2O3时玉米秸秆、稻壳和锯末的最大NO峰值降低率分别为18.71%、29.88%和18.66%。增加Fe2O3的添加剂量,NO峰值降低率增大。在900℃时添加0.52 mg的Fe2O3,玉米秸秆、稻壳和锯末,最大NO峰值降低率分别为28.02%、32.56%和27.12%。纳米Fe2O3降低NO排放的效果要好于纳米单质Fe。根据生物质燃烧过程中氮的转化路径与机理,推测Fe2O3主要通过将NO的前驱物HCN还原为N2,从而抑制NO的生成;单质Fe则主要通过直接将生成的NO还原为N2来减少NO的排放。

To control the NO emissions during the biomass combustion,a method to add nano iron-based additives to biomass was used to study the inhibition of NO production during the combustion process. In an one-dimensional tubular furnace,the NO emission characteristics of three typical kinds of biomass( corn stalk,rice husk and sawdust,100 mg)containing the nano Fe_2O_3 additive were experimentally studied at a temperature of 700 ℃,800 ℃ and 900 ℃ respectively. It has been found that Fe_2O_3 can effectively lower the peak value of NO. With an increase of the temperature,the descending rate of the NO peak value of corn stalk and sawdust will increase,however,that of the rice husk will arrive at its maximum value at 800 ℃. At different temperatures,when a weight of 1 mg Fe_2O_3 is added,the maximum descending rates of the NO peak values of corn stalk,rice husk and sawdust will be 18. 71%,29. 88%and 18. 66% respectively. When a weight of 0. 5 to 2 mg Fe_2O_3 is added,the maximum descending rates of the NO peak value of corn stalk,rice husk and sawdust will be 28. 02%,32. 56% and 27. 12% respectively at 900 ℃. The effectiveness of the nano Fe_2O_3 to lower the NO emissions is superior to that of the nano single substance Fe. According to the path and mechanism governing the conversion of N during the biomass combustion process,it can be predicted that Fe_2O_3 will mainly reduce the precursor HCN of NO to N_2,thus inhibiting the production of NO whilethe single substance Fe will mainly reduce the NO produced to N_2 to lower the NO emissions.