回转窑褐煤富氧燃烧氮氧化物产生机理及控制技术的研究

Flue gas denitrification technology usually applies to controlling of NOx emissions at home and abroad. Due to very complicated technology, it hasn't been widespread in rotary kiln industry such as cement industry now. According to the previous research on combustion characteristic of lignie under oxygen-enriched conditions, this project intends to adopt oxygen-enriched combustion technology to eliminate temperature NOx from the source, and utilize porous adsorption material that is a kind of low-cost silicate made from coal-based solid waste to solve the problem about controlling NOx emission in rotary kiln industry. Based on the lignite resource advantage in the Inner Mongolia region, the project will research the relationship of technological conditions and nitrogen conversion of fuel to reveal the NOx emissions laws under oxygen-enriched combustion of lignite in the rotary kiln, simulate oxygen-enriched combustion characteristic distribution of lignite the rotary kiln including temperature, velocity, turbulence intensity,recirculation region, carbon burnout rate, pulverized-coal particle concentration, NO, CO and O2 concentration, in order to reveal the generation mechanism of NOx and research controlling methods. Moreover, this project intends to research modification of porous silicate adsorption material made from coal-based solid waste, and develop DeNOx adsorbent to reveal absorption mechanism and ensure optimum absorption conditions. The project, having important theoretical and practical significance, will reveal the generation mechanism of NOx under oxygen-enriched combustion of lignite in rotary kiln and establish new DeNOx technology.

NOx污染控制国内外普遍采用烟气脱硝技术，由于工艺技术难度高，目前在水泥等回转窑行业没有普遍采用。在前期研究富氧增强褐煤燃烧性能的基础上，本项目提出采用褐煤富氧燃烧技术从源头上消除温度型NOx，同时利用煤基固废制备的多孔硅酸盐吸附材料进行低成本烟气吸附脱硝，以解决回转窑NOx污染控制难题。基于内蒙古地区的褐煤资源优势，实验研究燃烧工况与燃料氮转化率的关系，明确回转窑褐煤富氧燃烧NOx排放规律，模拟回转窑内褐煤富氧燃烧的温度、碳燃尽速率、煤粉颗粒浓度、NO浓度、CO浓度和O2浓度分布等燃烧特性，揭示回转窑内褐煤富氧燃烧下NOx排放机理，提出消减对策。在此基础上，对前期研发的煤基固废制备的多孔硅酸盐吸附材料进行改性研究,开发脱硝专用吸附剂,探明吸附剂机理，确定最佳吸附条件。研究结果将揭示回转窑富氧褐煤燃烧NOx产生机理，建立脱硝新技术，具有一定的理论和实用价值。

目前，水泥熟料煅烧工业的NOx排放量占全国工业生产NOx排放总量的10 %以上，仅次于火力发电，但是水泥熟料生产企业仅依靠低氮燃烧和燃料分级控制NOx排放，缺乏有效的控制技术。基于前期研究富氧增强褐煤燃烧性能的基础上，本项目提出采用褐煤富氧燃烧技术从源头上消除温度型NOx，通过烟气循环降低燃料型NOx，从而实现回转窑褐煤燃烧NOx的源头控制；同时，利用煤基固废制备的多孔硅酸盐吸附材料进行低成本烟气吸附脱硝，以解决回转窑NOx污染控制难题。基于内蒙古地区的褐煤资源优势，利用快速高温反应实验来研究反应气氛与燃料氮转化率的关系，明确回转窑褐煤富氧燃烧NOx排放规律，模拟回转窑内褐煤富氧燃烧的温度、碳燃尽速率、煤粉颗粒浓度、NO浓度、CO浓度和O2浓度分布等燃烧特性，揭示回转窑内褐煤富氧燃烧下NOx抑制机理，提出消减对策。在此基础上，对前期研发的煤基固废制备的多孔硅酸盐吸附材料进行改性研究，开发脱硝专用吸附剂，探明吸附剂机理，确定最佳吸附条件。所得结论主要包括：与空气燃烧相比，两种富氧燃烧工况(20O280CO2和35O265CO2)的NO排放浓度分别降低了8.50%和24.67%，考虑到烟气循环效应，NO排放总量分别减少了66.83%和72.83%。另外，本研究在确定最佳烟气条件下，进一步考察了改性硅基多孔材料对NO、NO2的脱除效果。结果表明：G-1、G-5改性剂对脱除NO2具有较好的脱除效果，脱除率均达到100%，对NO脱除率基本没有提高；G-2对NO的脱除率提高了20%左右，对NO2的脱除率基本没有提高，但对于混合后的NO和NO2有一定的脱除效果。经G-2改性的硅基多孔材料，当温度升高到200℃时，NO2脱附率为58.73%，NO脱附率为86.04%。