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研究报告

Experiment and numerical simulation on the NO_x emission in iron ore sintering

摘要：为了探明铁矿石烧结过程中影响氮氧化物排放的主要因素，采用烧结杯实验和数值模拟方法对铁矿石烧结过程中的氮氧化物排放进行了研究，实验通过变化焦炭配比和二元碱度，分析了不同焦炭配比和碱度下焦炭氮转化率.结果发现，焦炭对氮氧化物的还原作用比较大，焦炭质量分数每提高0.5%，则焦炭氮转化率减少3%左右，而碱度的作用主要体现在烧结矿的下层，在烧结床下层，应适量添加熟石灰.将焦炭颗粒按照粒径分为粘附颗粒和核心颗粒，通过建立制粒模型，对3个工况的氮氧化物排放进行了分析.烧结程序计算结果说明，粘附层的成分对焦炭氮转化率的影响也是比较大的，如果粘附层含有较多的矿石，则会降低氮氧化物和焦炭的气化反应，减少NO_x还原.

Abstract：To study the factors that affect NO_x emission in the iron ore sintering process, sintering pot experiments and numerical simulations were carried out in this work. The experiments were conducted by varying coke and binary alkalinity addition levels. The conversion ratio of char nitrogen under different coke and alkalinity levels were analyzed. Results showed that the reduction of nitrogen oxides by coke was significant. With every increase of coke mass fraction by 0.5%, the conversion ratio of char nitrogen was decreased by approximately 3%. The effect of alkalinity on char nitrogen conversion is mainly shown in the lower sintering bed. It is suggested that hydrated lime can be added into the lower bed to reduce char nitrogen conversion. Coke particles were divided into the adhering and nuclear particles based on particle size. With the establishment of a granulation model, the nitrogen oxide emissions of three sintering cases were analyzed. Results predicted by an iron ore sintering model showed that the composition of the adhering layer had a large impact on the conversion of char nitrogen. When the adhering layer contains more iron ores, the gasification reaction between nitrogen oxides and coke will be reduced, resulting in lower NO_x reduction rates.