某330 MW机组烟气脱硝系统超低排放性能诊断与分析

摘要

The anticipated target of NOxemission control have not been reached in some power plants after the ultra-low emission retrofit project. To solve this problem, taking a 330 MW ultra-low emission unit as an example, onsite investigation was conducted and the operation data of a 15 500 h flue gas denitrification unit was collected. The operating catalyst was also sampled and tested. Besides, the causes of excessive NOxemission were investigated individually. The research results show that the decline of denitrification efficiency is attributed to low design margin of SCR denitrification, low content of main active component V2O5as well as the decrease of catalyst micropore number and active point number. In addition, the high NOxconcentration at the inlet of the reactor, the frequent load changes, and untimely ammonia spray response cause the NOxemission at the outlet to exceed 50 mg/m3. In order to ensure that stable emission standards are met, it is suggested that the optimal operation of the boiler should be strengthened to avoid the large fluctuation of NOxconcentration and improve the response speed of ammonia injection. One extra layer of catalysts is also advised and the existing two layers of catalyst should be regenerated.%超低排放改造后,一些电厂NOx排放未达到预期目标.为解决此类问题,以某330 MW超低排放机组为例,对运行了15500 h的烟气脱硝装置进行现场勘查、运行资料收集,并对运行催化剂进行取样检测,逐一排查NOx超标排放的原因.研究结果表明:SCR脱硝系统设计裕量低,催化剂主活性成分V2O5含量偏低,催化剂微孔数与活性点位数减少导致脱硝效率下降,加之反应器入口NOx浓度偏高、负荷变化频繁、喷氨响应不及时,造成SCR脱硝装置出口NOx浓度超过50 mg/m3.建议加强锅炉优化运行,尽量避免入口NOx浓度大幅度波动,提高喷氨响应速度,并应新增1层催化剂,将现有2层催化剂进行再生,以确保NOx排放浓度稳定达标.