低温脱硝催化剂在火电厂锅炉启动期间的中试应用

Pilot-scale application of low temperature deNO_x catalyst for start-up of boiler in thermal power plant

高温选择性催化还原(SCR)脱硝装置在燃煤发电机组点火初期无法使用(烟气温度较低),导致烟气中氮氧化物一段时间内大幅超标排放。依托石河子天富南热电有限公司125 MW机组建立的低温脱硝侧线实验平台(1 000 m3·h-1),探讨浸渍法制备的Mn-Ce/Al2O3低温脱硝催化剂在机组点炉期间的处理效率和影响因素。结果表明,Mn-Ce/Al_2O_3低温脱硝催化剂表面具有丰富的介孔结构,且主要以Ce4+和高价态的Mn存在,有助于提高催化剂的低温活性。在现有高温SCR脱硝装置运行正常前,低温脱硝催化剂在烟气温度100℃时可维持约70%的脱硝率,处理后烟气中的氮氧化物基本达到现有排放标准;在本次点炉期间(4 h),低温脱硝催化剂的使用可减少约700 kg氮氧化物的排放。烟气湿度对低温脱硝催化剂效率的影响较大;考虑到点炉期间烟气参数的实际情况(湿度较低),Mn-Ce/Al_2O_3低温脱硝催化剂在解决点炉期间氮氧化物超标排放时具有较大的潜力。

High temperature selective catalytic reduction（ SCR） denitrification device can not be used in the early ignition stage of coal-fired power generation unit（ temperature of the flue gas was lower）,which will lead to excessive emission of nitrogen oxides（ NOx） in flue gas over a period of time. In this study,side line experimental platform for low temperature denitrification（ 1 000 m3·h-1） established relying on the 125 MW unit of Tianfu South Thermoelectric in Shihezi was used to explore the efficiency and influence factors of Mn-Ce/Al2O3 low temperature denitration catalyst by impregnation method during ignition of the furnace. The results showed that the surface of Mn-Ce/Al2O3 catalyst has rich meso-pores. In additional,the presence of Ce4 ＋and high valence Mn species in the surface of catalyst improved the activity of the catalyst at low temperature. The efficiency of de NOx could maintain about 70% at 100 ℃and basically achieve the existing emission standards before the normal operation of the high temperature SCR unit. During ignition of a boiler（ 4 h）,approximately 700 kg NOx emissions were reduced by using low temperature de NOx catalyst. In addition,the humidity of flue gas has a great influence on the efficiency of low temperature denitration catalyst,therefore,Mn-Ce/Al2O3 SCR catalyst at low temperature has a great potential to control the excessive NOx emission from starting fire to normal operating when considering the actual condition of flue gas（ humidity of the flue gas was lower）.