Formation Behavior And Emission Reduction Technology Of No_x In Sintering Process

NOx emissions from the sintering process account for fifty percent of the total emissions from the steel plant. Its effective reduction is of great significance to the sustainable development of iron and steel industry. In this paper, the laws and generate behavior of NOx emissions are studied, reduction technologies of NOx emissions in sintering process are developed.The laws of NOx emissions during sintering process shows that NOx concentration increases rapidly after ignition, then it remains stable during the sintering process and declines fast when it reaches the burn-through-point. The effect of sintering parameters on NOx emission indicates that Fuel N conversion rate increases first and then decreases with the increase of sinter mix moisture and coke ratio; the conversion rate declines with the increase of lime ratio, sinter basicity and the bed depth.The generation features of NOx are studied. The result shows that the content of N and fixed carbon in the fuel has little effect on the conversion ratio of N; the content of NOx and Fuel N conversion rate decreases as the decrease of volatile components and the increase of the reactivity. The Fuel N conversion rate gets minimum value when the size is in the range of1-3mm.Lime and iron oxides in the sintering materials have promotional effect on the conversion of Fuel N, while the calcium ferrites form during the sintering process have an adversely affect. Fuel N conversion rate of sintering process is higher than that of single fuel. In the sintering process, Fuel N conversion rate shows a tendency of descend as the rise of the temperature and the decrease of the O2content or the increase of CO2content.Comparing with fuel uniformly distributed in the granular or not being wrapped, when fuel is wrapped inside the granular, Fuel N conversion rate is lower. Fuel N conversion rate reduce from61.45%to53.10%and the production and quality indicators are not affected.On the base of fuel pre-granulation, when flux is selective distributed or use of biomass charcoal to replace some coke powder, the NOx emissions can be further reduced.