【摘要】 SCR系统内烟气速度场和氨氮摩尔比的均匀性对机组运行经济性影响很大。国内某660 MW燃煤机组为改善SCR系统内堵灰和氨逃逸现象,对系统内流场和喷氨格栅(AIG)进行了优化改造,为证明改造方案的效果,利用FLUENT软件对该机组在BMCR负荷下进行了数值模拟,对比分析了系统内和首层催化剂入口截面速度、流向以及氨氮摩尔比分布。结果表明:通过导流板优化流场,系统内速度分布均匀,首层催化剂入口烟气速度相对标准偏差为7. 2%(<15%),流向最大偏角为7. 2°(<10°);通过AIG和扰流板替代原涡流式静态混合器,首层催化剂入口氨氮摩尔比偏差为2. 56%(<5%),均满足设计要求。相关工程改造经验可为同类型SCR系统改造提供参考。更多还原

【Abstract】 The uniformity of the flue gas velocity field and the NH₃/NO_x molar ratio in the SCR system has a great impact on the economics of the power plant operation. To improve the ash plugging and ammonia escaping in SCR system,a domestic 660 MW coal-fired station optimized and modified the flow field and ammonia injection grid（AIG） in the system. To prove the effect of the retrofit scheme,it conducted numerical simulations by using FLUENT software and compared and analyzed the velocity,flow direction and ammonia-nitrogen molar ratio distribution of the first layer catalyst inlet section. The results show that the flow field is optimized by the deflector and the velocity distribution in the system is uniform. The relative standard deviation of velocity of the first catalyst inlet is 7. 2%（<15%）,and the flow deflection angle is 7. 2°（< 10°） . By replacing the original vortex static mixer with an AIG and spoilers,the relative standard deviation of ammonia-nitrogen molar ratio of the first catalyst inlet is 2. 56%（<5%）,which meets the design requirements. Relevant engineering transformation experience provides reference for the transformation of SCR systems of the same type.更多还原