摘要
燃煤机组锅炉在低负荷运行状态下,SCR(选择性催化还原)进口烟道沿宽度方向烟温偏差很大,外侧低中间高,偏差最高可达17~18℃。烟温低的区域处在催化剂低限值下面了,而喷氨枪仍然整个烟道均匀地在喷,造成氨气与烟气混合不均致使脱硝效率降低,同时对催化剂也产生不良影响。针对这一现象,本课题在SCR反应器入口烟道外侧加装均流挡板,使烟气通流面积随负荷变化而变化,充分保证喷氨枪断面上的流速,提高充满度确保烟气流场均匀,与氨气充分混合起到匀质的效果,从而提高脱硝效率。并使外侧催化剂处于休息状态,延长了催化剂寿命。工程改造后进行性能测试,均质后的效果能将NO_x值降低32~40 mg/Nm^3,可实现20 mg/Nm^3的近"0"排放,喷氨流量降低11%左右。获得了环保与经济的双重收益。
Coal-Fired unit boiler runs at low load, SCR inlet flue temperature changes a lot along width direction, which shows outsides temperature is low and middle ones is high and deviation is around 17~18C . Ammonia gun is working in whole flue pipe while low flue temperature is below low limit value of catalyst and uneven ammonia and flue mixture results in low denitrification efficiency with bad influence on catalyst. Focus on fixing it, the author installs current sharing baffle outside of SCR reactor inlet flue, which makes flue flow area change with load changes and guarantee ammonia flow velocity to improve much evener flue distribution mixing with ammonia to increase denitrification efficiency with good influence on catalyst.The performance test was carried out after engineering renovation and the effect of homogenization can reduce NOx value by 32-40 mg/Nm3, which achieves ＇ Zero＇ emission of 20 mg/Nm3 and reduce ammonia injection rate by about 11%. It means double benefits of environment protection and economyvalue.
出处
《上海节能》
2017年第11期660-665,共6页
Shanghai Energy Saving
