超低排放改造前后SCR脱硝装置性能评价分析

Comparative Research the Performance of SCR Denitrification Device Before and After the Ultra-low Emission Retrofit in Coal-fired Units

选取2台燃煤机组进行实测,分析了超低排放改造前后选择性催化还原技术(selective catalytic reduction,SCR)脱硝装置出口NOx浓度、氨逃逸率以及烟气在线监测系统所测SCR脱硝出口与烟囱入口NOx浓度;同时,分析了超低排放改造机组的催化剂、空预器垢样。结果表明,机组排放超低改造后存在NOx浓度分布均匀性变差和逃逸氨浓度急剧增加问题,并由此造成空预器硫酸氢铵堵塞严重,催化剂活性成分流失较为严重,硫酸盐和碱土金属元素含量上升明显。为解决上述问题,文中提出多点监测、喷氨优化、催化剂定期测试和空预器冷端更换镀搪瓷元件等措施。

Two different types of coalfired units are selected to compare the NOx concentration,the ammonia escape rate andthe NOx concentration of the SCR denitrification device outlet and the chimney inlet measured by CEMS before and after theultralow transformation. At the same time ,on the ultralow emissions after the transformation of the air preheater dust andcatalyst samples are analyzed. The results show that after the ultralow emission of the unit,there are some problems that thebad uniformity of the NOx concentration distribution and the increase of the escaping ammonia concentration,resulting in seriousammonium hydrogen sulfate blockage in air preheat heat. Catalyst active component of velocity is relatively serious,sulfate andalkaline earth metal elements content increased significantly. In order to solve the above problems,it is proposed to adoptmultipoint monitoring,spray ammonia optimization,catalyst regularly tested,airconditioner coldend replacement of enamelenriched elements and other measures.