Coke breeze combustion and emission behaviors of CO and NO during iron ore sintering

Abstract

CO emission reduction, especially the coordinated emission reduction of CO and NO in sintering flue gas, has attracted widespread attention in the world. The effects of different sintering raw materials, temperature and atmosphere on coke breeze combustion and CO and NO emission behaviors were studied. The results show that, sintering raw materials significantly improved the combustion performance of coke breeze, and promoted the simultaneous reduction of CO and NO emissions. Among them, Dolomite had the strongest catalytic effect, which reduced the apparent activation energy of coke breeze combustion reaction from 99.35 kJ/mol to 56.11 kJ/mol, and the emission reductions of CO and NO were as high as 47.84 % and 73.25 %, respectively. The catalytic ability of the raw materials components was CaO ＞ MgO ＞ Fe2O3. However, during the combustion process of coke breeze without raw materials, the reduction of NO by CO was affected by the atmosphere of the boundary layer, the conversion of N element was negatively correlated with the content of CO. When the temperature increased from 600 ℃ to 1 050 ℃, the combustion performance was improved, the thickness of the combustion zone was reduced by 47.92 %, the total emission of CO was decreased by 65.39 %, and the total emission of NO was increased by 23.05 %. The O2 concentration decreased from 21 % to 10 %, the combustion rate decreased, the combustion zone thickened by 90 %, incomplete combustion was promoted, the total emission of CO increased by 101.15 %, and NO decreased by 21.09 %. The CO2 concentration increased from 5 % to 15 %, the gasification reaction was enhanced, the combustion time was extended, the combustion zone thickened by 45.9 %, the total emission of CO increased by 87.12 %, and the reducing atmosphere was enhanced, which was conductive to the reduction of NO by CO, and the total emission of NO decreased by 50.59 %.