不同蒸汽喷吹条件下烧结烟气的NO_(x)和SO_(2)排放规律

NO_(x)and SO_(2)emission rules of sintering gas under different steam spraying conditions

为降低烟气中NO_(x)和SO_(2)的排放质量浓度,提高固体燃料的燃烧效率,本文基于某钢铁厂的烧结原料开展50 kg级烧结杯试验,研究向烧结料面喷吹蒸汽条件下喷吹总量、喷吹流量及开始喷吹时间等因素对烧结过程NO_(x)和SO_(2)排放的影响。结果表明:点火8 min后向料面连续喷吹蒸汽15 min,当喷吹流量为0.02 m^(3)/min时,烧结烟气中NO_(x)和SO_(2)排放质量浓度分别降低11.75%、13.25%,并且烧结矿的产、质量指标亦有优化。蒸汽的加入有利于固体燃料分子键的断裂,加速固体燃料挥发分中HCN和NH3的析出进程,同时增强了烧结料层的局部还原性气氛,进而促进烧结过程NO的异相还原反应,降低了NO_(x)的排放质量浓度;向料面喷吹蒸汽会使过湿层增厚,使SO_(2)在过湿层中逐渐被吸收,当过湿层消失时,SO_(2)瞬间释放不充分,从而降低其排放质量浓度,并且延迟其排放峰值。本文研究的蒸汽喷吹工艺制度有利于烧结生产提质降耗,可为钢铁企业生产提供参考。

In order to reduce the mass concentration of NO_(x)and SO_(2)emission in the flue gas and improve the combustion efficiency of solid fuel,a 50 kg sinter pot test is carried out based on the sintering raw material of a steel plant,and the effects of total injection,injection flow and start spraying time on NO,and SO2 emissions during the sintering process under the condition of spraying steam to the sintering charge level are studied.The results show that,after ignition for 8 min,steam is continuously sprayed to the charge level for 15 min,and when the injection flow is 0.02 m^(3)/min,the mass concentrations of NO_(x)and SO_(2)emissions in the sintering gas are reduced by 11.75%and 13.25%,respectively,and the production and quality indexes of sinter are also optimized.The addition of steam is conducive to breaking the molecular bonds of solid fuels,accelevating the precipitation process of HCN and NH,in the volatiles of solid fuels,enhancing the local reducing atmosphere of the sinter bed,thereby promoting the heterogeneous reduction reaction of NO in the sintering process and reducing the mass concentration of NO_(x)emission.Spraying steam to the charge level will thicken the superhumid layer,so that SO_(2)is gradually absorbed in the super-humid layer,and when the super-humid layer disappears,SO,is insufficiently released instantaneously,thereby reducing its emission mass concentration and delaying its emission peak.The steam spraying process system is conducive to improving quality and reducing consumption in sintering production,and can provide references for the production of iron and steel enterprises.