300 MW燃煤发电机组S CR脱硝分区喷氨性能评估

Performance Evaluation of Ammonia Injection in Zoned SCR for a 300 MW Coal-fired Power Generation Unit

针对某300 MW燃煤机组SCR脱硝分区喷氨改造方案进行了CFD仿真模拟,获得了脱硝SCR内的流场和氨浓度分布特征;并基于分区精准喷氨的原理和机制,对前端分组格栅喷射的氨气与后端氮氧化物测点对应进行了评估。结果表明,现有脱硝装置由于导流设计不合理,导致系统的氨浓度分布不均匀,将诱发过量喷氨问题;在分区喷氨格栅喷出的氨气在催化剂入口截面横跨2~4分区,与设计假定的一一对应关系存在较大差异,精准喷氨的改造效果将受较大影响。

A CFD simulation was conducted on the ammonia injection retrofit scheme for a 300 MW coal-fired unit's SCR(Selective Catalytic Reduction) de-NOxsystem.This simulation helped to obtain the flow field and ammonia concentration distribution within the SCR.Based on the principle and mechanism of precise zoned ammonia injection,an evaluation was performed on the correlation between the ammonia injected at the front grouped grilles and the nitrogen oxides measuring points at the back.The results indicate that the current de-NOxdevice,due to unreasonable guide design,leads to uneven distribution of ammonia concentration throughout the system,which could induce excessive ammonia injection issues.The ammonia ejected from the zoned injection grilles spans zones 2~4 at the catalyst inlet cross-section,significantly differing from the designed one-to-one correspondence assumption,greatly affecting the effectiveness of the precision ammonia injection retrofit.