SNCR和SCR系统

ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084SNCR和SCR系统ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation2SNCR系统ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation3CO(NH2)2+2NO+1/2O22N2+CO2+2H2O4NO+4NH3+O24N2+6H2O•通过喷入含氮的化学试剂将烟气中的NOx转化为元素氮和水SNCR基本过程ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation4SNCR技术•1975年Exxon提出了针对燃烧产物，采用氨的第一个SNCR专利•1980年电力研究所(EPRI)获得了用尿素的SNCR技术•EPRI将专利实施许可给了NALCO/燃料技术公司.燃料技术公司和NALCO已经分离.现在燃料技术公司独自提供这技术•Exxon和EPRI专利已经过期ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation5电力试验研究所(EPRI)Patents,Circa1975在富燃料燃烧条件下单层尿素喷射在贫燃料燃烧条件下单层尿素喷射燃料技术公司(拥有42仍有效的美国专利,250多个仍有效的世界专利）各种不同的增强装置多阶段喷射器“RightSideoftheSlope”内混/外混喷射器低温化学品知识产权ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation6•初始NOx浓度•温度•停留/反应时间•摩尔比/化学剂利用率•喷射与混合•温度与气流分布均匀性•化学剂的处理•付产物的形成•积灰•对飞灰特性的影响•化学剂的成本SNCR–关键参数ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation7•SNCR仅在很窄的一个温度区间内才有效•有效性还与上述温度区间内的停留时间有关•试剂混合与分布(可能需要多层冷却的喷射枪）•在煤粉炉的负荷变化时需要多点的喷射，复杂的控制依据温度与停留时间。•特别适合于CFB(接近最理想的温度,混合和停留时间)成功SNCR技术过程的关键参数ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation8NOxin=200ppm,3%O2停留时间和温度对NOx还原的影响ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation9SCRUpto95%2ppm550to750°FYes单平面大机组与小机组$100to$160/KW是NOX还原率氨泄漏运行温度催化剂喷射点应用改造费用飞灰的适销性SNCR25to50%5-20ppm1500to1800°FNo多层小机组$15to$30/KW??(高NH3)SCR/SNCR比较ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation10罐槽吹灰器SCR系统ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation114NO+4NH3+O26NO2+8NH34N2+6H2O7N2+12H2O(CATALYST)(CATALYST)SCR用氨(NH3)将NOx转化为无害的元素氮(N2)and水蒸汽(H20)注:这些反应在~1500°F(SNCR)在没有催化剂条件下也会进行，但在700°F，必须要有催化剂才能使并反应可能SCR基本过程ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation12催化剂空预器省煤器旁路流动导向器AIGNH3Tank含水的NH3系统Blower汽化器流向烟囱的干净烟气静态混合器管内加热器(仅在含水时使用）未来催化剂热空气FROMIDHX流向AIG的氨/空气混合物冷空气TOIDHX典型的SCR按装ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation13适当的催化剂规格与选择对于成功SCR是致关重要的类型:提供商:HoneycombIHI,Cormetech,SKPlateHitachi,SiemensFiberBaseHaldor,ZosenZoeliteNorton,Engelhard催化剂选择ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation14烟气条件流量烟气温度组成:H2O,NOx,O2,SO2含尘量(间距,磨损)设计要求NOx还原率,氨泄漏率和设计寿命系统压降流动分布温度和NH3/NOx混合结果烟气毒害催化剂的可能(碱金属,V,As,Ca)操作方法与条件(负荷范围)SO2向SO3氧化率价格和计算的费用(用电,钢和反应器费用,安装费用等.)影响催化剂选择的因素ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation15•积灰和腐蚀•碱金属:钠(Na),钾(K).NaSO4andK2SO4可以与催化剂上的活性位•砷(As):气态砷(As2O3)可以与活性位反应并使催化剂表面固化•钒(增加活性但将增加SO2向SO3的转化率)•钙CaO+SO3--------CaSO4堵塞孔隙及NH3NOx扩散.但是,CaO能帮助减少砷的影响:3CaO+As2O3+O2------Ca3(AsO4)2(solid)CATALYST影响催化剂寿命的主要因素ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation16Lb.MMBtuSlipNOX减少效率出口NOX浓度氨泄漏初始加载增加催化剂层时间催化剂管理方法（例子）ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation17几乎极大部分催化剂的配方中都含有五氧化二钒以加强反应性。钒也是SO2氧化成SO3的催化剂SO3和NH3的存在会导致形成氨盐增加的SO3会增加H2SO4形成的可能性-腐蚀与酸雾“蓝”羽形烟催化剂设计的考虑-SO2向SO3氧化ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation18硫酸氨(AS)SO3+2NH3+H2O---(NH4)2SO4小颗粒,小于10微米对细颗粒污染有贡献.细小的，白色的高反射率的颗粒物(可见的烟雾)硫酸氢氨(ABS)SO3+NH3+H2O----NH4HSO4ABSis粘性的,腐蚀的物沉积在空预器或催化剂上(在低负荷下)为避免在催化剂上的形成要规定最低的运行温度和省煤器的旁路催化剂设计考虑–硫氨盐类化合物ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation19合适的流动分布和氨/NOx混合对于SCR性能是很重要的。计算流体动力学(CFD)模型用来评价静态混合器的热混合性能实际的流动模型-1/12比例获得均匀的流动分布获得在SCR反应器入口均匀的氨和温度分布减少压力降流动模型ParticleAndCombustionEngineeringResearchGroupDepartmentofThermalEngineering,TsinghuaUniversity,Beijing,100084April20,2003ChinaPowerGroupDelegation20流动模型建立Parti