高温催化条件下燃煤烟气SNCR脱硝实验研究

Research on SNCR Denitrification of Coal-fired Flue Gas under High Temperature Catalytic Conditions

通过浸渍法将稀土尾矿中的活性成分负载到活性炭颗粒上制得脱硝催化剂,探究烟气温度、催化剂粒径以及NH3/NO比例因素对高温燃煤循环流化床锅炉烟气SNCR脱硝效率的影响。通过烟气分析仪结合红外光谱分析检测烟气组分含量并计算脱硝率,利用TG、SEM、XRD、TPD、TPR等技术手段表征催化剂性质和微观结构。结果表明,制备的催化剂孔隙发达,比表面积较大,对气体的吸脱附效果较好。烟气温度和氨氮比是脱硝率的重要影响因素。脱硝率随烟气温度的增加呈先上升后下降的趋势;随着NH3/NO比例的增加、催化剂粒径的减小和添加量的增加,脱硝率均呈现先升高后降低的趋势;催化剂的存在对提高燃煤循环流化床锅炉烟气SNCR脱硝效率具有明显的促进作用。催化剂中的部分Fe、Ce、La、Nd、Pr等组分在高温下容易与活性炭结合,形成共熔体,有利于联合协同催化脱硝反应的进行;制备的脱硝催化剂相对于原矿有较高的比表面积、酸量与还原性能力。

The denitration catalyst was prepared by impregnating the active components of rare earth tailings onto activated carbon particles.The influence of flue gas temperature,catalyst particle size and NH3/ NO ratio on the SNCR denitrification efficiency of the flue gas produced from high temperature coal-fired circulating fluidized bed boiler was investigated.The content of flue gas components was determined by flue gas analyzer combined with infrared spectrum analysis and then denitrification rate was calculated.The properties and microstructure of the catalyst were characterized by TG,SEM,XRD,TPD and TPR.The results show that the prepared catalyst exhibits high porosity,large specific surface area and good gas adsorption and desorption properties.Flue gas temperature and ammonia nitrogen ratio are important factors affecting the denitrification rate.With the increase of flue gas temperature,denitrification efficiency increases first and then decreases.With the increase of NH3/NO ratio,the decrease of catalyst particle size and the increase of catalyst addition,denitrification efficiency increases first and then decreases.The presence of the catalyst plays a significant role in improving the SNCR denitration efficiency of the coal fired circulating fluidized bed boiler flue gas.A part of Fe,Ce,La,Nd,Pr and other components of the catalyst are easily combined with activated carbon at high temperature to form a co-melt,which is conducive to the progress of the joint synergistic catalytic denitrification reaction.The prepared denitrification catalyst has higher specific surface area,acid content and reducibility than the raw ore.