NH_3选择性非催化还原含硫烟气中NO_x的实验研究  

Experimental Study of Selective Non-catalytic Reduction of NO_xby NH_3in Flue Gas Containing SO_2

作　　者：唐志雄[1] 曾环木[1] 岑超平[1] 陈志航[1] 陈定盛[1] 方平[1] 陈雄波[1] 

机构地区：[1]广东省水与大气污染防治重点实验室(环境保护部华南环境科学研究所),广东省广州市510655

出　　处：《中国电机工程学报》2013年第20期34-39,8,共6页Proceedings of the CSEE

基　　金：广东省重大科技专项(2010A080804022);广东省战略新兴产业核心技术攻关(2011A032303002)~~

摘　　要：为考察部分烟气中高浓度SO2对选择性非催化还原法(electivity non-catalytic reduction,SNCR)脱硝的影响,采用固定床反应器开展了含硫条件下,温度775～975℃、氨氮摩尔比([NH3]/[NO])0.9～3.0、O2浓度5%～21%、SO2浓度0～0.022%和停留时间7.9～23.6 s对NH3选择性非催化还原NOx影响的实验研究。实验结果表明:对比无硫及含硫烟气,随着温度的上升,NOx转化率均逐步提高,特别是向烟气中添加SO2后脱硝效率明显提升,且剩余的氨与SO2发生反应形成硫酸铵盐,因此氨逃逸量极少;氨氮比小于1.6时,脱硝效率随氨氮比的增加而迅速上升,当氨氮比大于2.4时,氨逃逸浓度随着氨氮比的增长而迅速增加;随着O2浓度的增加,NOx的转化率逐渐降低,O2浓度超过10%后脱硝效率趋于平稳;900℃条件下SO2的存在对NH3选择性还原NOx有一定的促进作用;随着停留时间超过9.4 s,在富氧、高温环境下,SNCR反应速率快且NH3氧化反应更易发生使得脱硝效率有所降低。Selective non-catalytic reduction of NOxby NH3 in flue gas containing high concentration of SO2 was studied.Experiments in a fixed bed reactor showed the effects of temperature（775-975 ℃）,molar ratio of NH3 to NOx（0.9-3.0）,O2 concentration（5%-21%）,SO2 concentration（0-0.022%）,and residence time（7.9-23.6 s） on denitrification efficiency.The results show that the NOx conversion in flue gas with and without SO2increases gradually with the rise of temperature.The denitrification efficiency improves significantly when SO2 is added to the flue gas,and the emission of NH3 is low because of the formation of ammonium sulfate by reaction between the remaining NH3 and SO2.The denitrification efficiency improves rapidly with the increase of the molar ratio of ammonia to nitrogen oxide（[NH3]/[NOx]） when [NH3]/[NOx] is below 1.6.The emission of NH3 increases rapidly with the increase of NH3/NOx when NH3/NOx exceeds 2.4.With the increase of the O2 concentration,the conversion of NOx is gradually reduced,and the efficiency of denitrification is stabilized when the O2 concentration exceeds 10%.The presence of SO2 promotes the reaction of NH3 selective reduction of NOx at 900 ℃.The denitrification efficiency decreases when the residence time of SO2 exceeds 9.4 s,this may be due to the faster SNCR reaction rate and the easier NH3 oxidation reaction under the conditions of high temperature and enriched oxygen.

关 键 词：选择性非催化还原 氮氧化物 氨 二氧化硫 

分 类 号：X511[环境科学与工程—环境工程]