Innovative coupled denitrification technology of SNCR and embedded SCR for pelletizing flue gas
LIU Chen1,2, HU Bing1,2, HU Pei-wei3, WEN Rong-yao1,2, YE Heng-di1,2, WEI Jin-chao1,2
1. Engineering Center of Sinter Pellet and Direct Reduction, Zhongye Changtian International Engineering Co., Ltd., Changsha 410205, Hunan, China; 2. National Engineering Research Center of Sintering and Pelletizing Equipment System, Changsha 410205, Hunan, China; 3. School of Resources and Environment Engineering, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China
Abstract：Under the situation of vigorously promoting green and low-carbon development in China, iron and steel industry comprehensively implements ultra-low emission of air pollutants from sintering and pelletizing. At present, the NOx emission reduction in pelletizing is imminent, which is related to the survival and development of pellet industry. Aiming at the problem of high NOx emission concentration in the domestic mainstream grate-kiln process of pelletizing production, research on coupled denitrification technology of selective non-catalytic reduction denitrification technology (SNCR) and embedded selective catalytic reduction denitrification technology (SCR) was conducted on the basis of system analysis for flue gas features and NOx distribution. The results show that pelletizing flue gas has the characteristics of high temperature (850-1 000 ℃ in the hood, 350 ℃ in the bellows), high NOx concentration (400-600 mg/m3) and small flow at the preheating stage of grate source, which is conducive to the collaborative coupling technology application of SNCR and SCR methods. When ammonia hydroxide is used as reducing agent, flue gas temperature is 830-930 ℃ and ammonia nitrogen mole ratio is 1.0-1.5, the denitrification rate of SNCR method can reach 40%-60%. The assembly of air balance plate on the grate can solve the cross air problem and prevent the disorderly diffusion of NOx. Then adopting NOx centralized treatment and implementing precise control of reducing agent dosage, can comprehensively improve the utilization efficiency of reducing agent and SNCR denitrification rate. Optimizing the structure of conical diffusion plate in SCR reactor was made by FLUENT numerical simulation method. When the horizontal angle of diffusion plate was tilted from 90° to 65°-75°, the distribution of flue gas velocity and ammonia reducing agent into the rectifier grid were more uniform. The optimized pelletizing flue gas SNCR coupling embedded SCR denitrification technology has a reasonable route, superior technical and economic performance, and a broad prospect for industrial application, which is a major innovation of China's pelletizing flue gas nitrogen oxide ultra-low emission technology.
刘臣, 胡兵, 胡佩伟, 温荣耀, 叶恒棣, 魏进超. 球团烟气SNCR与嵌入式SCR耦合脱硝新技术[J]. 钢铁, 2022, 57(3): 133-141.
LIU Chen, HU Bing, HU Pei-wei, WEN Rong-yao, YE Heng-di, WEI Jin-chao. Innovative coupled denitrification technology of SNCR and embedded SCR for pelletizing flue gas[J]. Iron and Steel, 2022, 57(3): 133-141.
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2022, Vol. 57 
