SCR法烟气脱硝后空气预热器堵塞及应对措施

选择性催化还原（SCR）法是目前燃煤电厂常用的烟气脱硝技术,火电厂加装SCR脱硝装置后易出现空气预热器（空预器）腐蚀和堵塞问题。通过某电厂实际案例,分析了SCR脱硝装置投运后对空预器运行造成的影响,并在分析原因的基础上给出应对措施。为控制空预器压差不继续增加,该电厂低负荷运行时SCR脱硝系统停止喷氨,正常运行时减少喷氨量,并在停炉后将空预器冷端换热元件更换为镀搪瓷元件。采取措施后运行一年多来,空预器压差正常,未出现严重的堵塞现象。

Analysis and Prevention of SCR DeNOx-Caused Air Preheater Clogging

The selective catalytic reduction(SCR) is commonly used for flue gas denitrification in coal-fired power plants. Corrosion and clogging tend to happen in the air preheaters after the SCR denitrification device is installed. In the case study of a power plant, the analysis of the impacts of the SCR denitrication device on the air preheater is conducted and some measures against the corrosion and clogging are proposed accordingly. To control the pressure difference of the air preheater no longer increasing, the ammonia is stopped spraying into the SCR denitrification device during low load operation while it is reduced during normal load operation. In addition, the heat exchange part of the air preheater heater is changed to an enameled one during the boiler shutdown. In more than a year of operation since then, the pressure difference has been normal and no severe clogging has ever happened.