Performance Evaluation of Ammonia Injection in Zoned SCR for a 300 MW Coal-fired Power Generation Unit
A CFD simulation was conducted on the ammonia injection retrofit scheme for a 300 MW coal-fired unit's SCR(Selective Catalytic Reduction)de-NOx system.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-NOx device,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.
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