H2 O和SO2对甲烷在金属铁表面还原NO的影响

摘要

为考察烟气中H2 O和SO2对甲烷在金属铁表面还原NO的影响，采用程序控温电加热水平陶瓷管反应器，在N2气氛和模拟烟气气氛中、300~1100℃下进行了脱硝实验研究，并对反应后铁样品的组成进行了X光衍射（ XRD）、场发射扫描电镜（ ESEM）和X 射线能谱（ EDX）分析。结果表明：在N2气氛中H2 O及SO2在高温下与NO竞争和金属铁反应，对金属铁还原NO有轻微的抑制作用。在加入甲烷的模拟烟气中，H2 O和SO2共存对甲烷在金属铁表面还原NO有一定促进作用。水蒸气在高温下对金属铁的氧化过程中，会生成更多相对疏松的Fe2 O3氧化层，有利于NO向内扩散与金属铁反应。加入7% H2 O和0.02% SO2的模拟烟气，反应段过量空气系数SR1＝0.7和燃烬段过量空气系数SR2＝1.2时，在1000℃，有、无H2 O及SO2时脱硝效率分别为96.9%和90.6%。%In order to investigate the effects of H2 O and SO2 on NO reduction by methane on the surface of iron,the NO reduction efficien-cy was tested at 300 ℃ to 1100 ℃ in an programmed electric heating horizontal ceramic tube reactor in N2 and simulated flue gas atmos-phere respectively. The component of iron samples after reaction were analyzed by XRD,ESEM and EDX. The results demonstrated that in N2 atmosphere,H2 O and SO2 reacted with iron in the competition reaction with NO on the surface of iron which inhabited NO reduction. In the simulated flue gas atmosphere,H2 O and SO2 promoted NO reduction by methane on the surface of iron. The formation of porous oxide layer of Fe2 O3 caused by the oxidation of water vapor on iron,enhanced the interaction of NO with metallic iron and then improved NO re-ductionefficiency.Whentheexcessairratiowas0.7inreactionzone(SR1)and1.2inburnoutzone(SR2),theNOreductionefficiency at 1000 ℃ was 96. 9% in the presence of 7% H2 O and 0. 02% SO2 ,compared with the value of 90. 6% in the absence of H2 O and SO2 .