Control of nitrogen oxides emission by selective non-catalytic reduction in preheating section during iron ore pellets production
Min Gan1, Wang Shu1, Zhi-yun Ji1, Zhi-an Zhou1,2, Xiao-hui Fan1, Bing Hu1,2, Guo-jing Wang1, Yuan Zhu1, Ya-fei Sun1,2
1 School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, Hunan, China; 2 Zhongye Changtian International Engineering Co., Ltd., Changsha 410205, Hunan, China
Control of nitrogen oxides emission by selective non-catalytic reduction in preheating section during iron ore pellets production
Min Gan1, Wang Shu1, Zhi-yun Ji1, Zhi-an Zhou1,2, Xiao-hui Fan1, Bing Hu1,2, Guo-jing Wang1, Yuan Zhu1, Ya-fei Sun1,2
1 School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, Hunan, China; 2 Zhongye Changtian International Engineering Co., Ltd., Changsha 410205, Hunan, China
摘要 Reducing the NOx emission from pelletizing process is of great importance to the green development of iron and steel industry. The flue gas temperature of preheating (PH) section during grate-kiln iron ore pelletizing process typically ranges within 850–1050 °C, which meets the temperature requirements of selective non-catalytic reduction (SNCR) for NOx. The in-bed SNCR behavior of NOx in the PH section was investigated, and the influence of relevant parameters was revealed. Results show that with the flue gas temperature rising, the denitration rate reached a peak value and then declined, where the appropriate temperature range was 950–1000 °C. Increasing the NH3/NO ratio (NSR) contributed to improving the denitration rate, and the appropriate NSR was 1.0. Oxygen content in the flue gas also showed an important influence on denitration rate, which reached a peak value and then dropped with the oxygen content rising. Under the condition of 18 vol.% oxygen content, the denitration reaction mainly occurred in the form of 4NO + 4NH3 + O2 = 4N2 + 6H2O. For restricting the competitive reaction of NH3 oxidation, the oxygen content in flue gas of PH section should be kept at an appropriate range. In general, the denitration rate reached about 25% in the PH section through spraying ammonia.
Abstract：Reducing the NOx emission from pelletizing process is of great importance to the green development of iron and steel industry. The flue gas temperature of preheating (PH) section during grate-kiln iron ore pelletizing process typically ranges within 850–1050 °C, which meets the temperature requirements of selective non-catalytic reduction (SNCR) for NOx. The in-bed SNCR behavior of NOx in the PH section was investigated, and the influence of relevant parameters was revealed. Results show that with the flue gas temperature rising, the denitration rate reached a peak value and then declined, where the appropriate temperature range was 950–1000 °C. Increasing the NH3/NO ratio (NSR) contributed to improving the denitration rate, and the appropriate NSR was 1.0. Oxygen content in the flue gas also showed an important influence on denitration rate, which reached a peak value and then dropped with the oxygen content rising. Under the condition of 18 vol.% oxygen content, the denitration reaction mainly occurred in the form of 4NO + 4NH3 + O2 = 4N2 + 6H2O. For restricting the competitive reaction of NH3 oxidation, the oxygen content in flue gas of PH section should be kept at an appropriate range. In general, the denitration rate reached about 25% in the PH section through spraying ammonia.
Min Gan,Wang Shu,Zhi-yun Ji, et al. Control of nitrogen oxides emission by selective non-catalytic reduction in preheating section during iron ore pellets production[J]. Journal of Iron and Steel Research International, 2022, 29(2): 215-222.
2022, Vol. 29 
