烧结烟气选择性催化还原脱硝补热装置的优化

Optimization of heating device for SCR denitration of sintering flue gas

烧结烟气选择性催化还原(SCR)脱硝系统补热烟气与热风掺混的均匀性是保证系统脱硝效率的关键。为提高烟风掺混的均匀性,基于伯努利方程设计了等压热风掺混装置,采用数值模拟的方法对全系统流场分布特性进行了研究。结果表明:等压掺混方式可实现大截面、短距离烟道内烟风的迅速混合;SCR脱硝催化剂入口截面温度和氨氮摩尔比均匀稳定,优化后的温度场温度偏差小于±5℃,氨氮摩尔比相对标准偏差小于5%;出口NOx含量为15~28mg/Nm3,低于50mg/Nm3的超低排放技术指标要求。

The uniform mixing of flue gas and heating hot blast plays an important role in ensuring the denitration efficiency of the selective catalytic reduction(SCR)denitration system of sintering flue gas.To improve the uniformity of the flue gas mixing,an isobaric hot-blast mixing device was designed based on Bernoulli equation.The flow field distribution characteristics of the entire system were studied by numerical simulation.The results show that:The isobaric mixing method can realize the rapid mixing of flue gas in large cross section within short-distance flue;The temperature and ammonia-nitrogen molar ratio at the cross-section of catalyst inlet are uniform and stable,the temperature deviation of the optimized temperature field is less than±5℃,and the relative standard deviation of the ammonia-nitrogen molar ratio is less than 5%;The outlet NOx content is 15-28 mg/Nm^3,which is lower than the requirement for ultra-low emission technical indicators of 50 mg/Nm^3.