【作者】 孟韵；

【导师】 钟秦； 张军营；

【作者基本信息】 南京理工大学 ， 应用化学， 2004， 博士

【摘要】 对煤燃烧过程中氮氧化物的前驱体、有害痕量元素及亚微米颗粒物的排放与控制进行了系统的研究。计算了非纯凝聚相复杂体系有害痕量元素的热力学平衡分布，得出了痕量元素的迁移转化规律。采用滴管炉研究了燃煤有害痕量元素砷的排放与控制，结果表明As在飞灰和底灰中的集散行为与煤种和炉膛温度有较大关系，TiO₂、CaCO₃和Ca（OH）₂等3种吸附剂对As均有抑制作用，As吸附效率可达73％。实验研究了燃煤中亚微米颗粒物的形成机理及排放控制，结果表明随炉膛温度的升高和煤含硫量的增加，亚微米颗粒物的排放量增大；TiO₂，CaCO₃和Ca（OH）₂均能抑制亚微米颗粒物的排放，抑制效果随炉膛温度的升高呈增大趋势，在1100℃～1250℃时达最大值。研制出针对亚微米粉尘的环流循环除尘系统，除尘效率可达97％以上。应用密度泛函理论，通过B3LYP／6-311++G^**木水平上的计算，研究了煤中有机氮的热解反应机理，建立了煤中吡啶型氮及吡咯型氮的热解模型。在管式炉氩气气氛中进行了煤热解实验，结果表明燃料氮在煤中以复杂结构存在，而不是简单的吡咯和吡啶结构；煤热解半焦中氮的形态与含量以及产物中的HCN和NH₃的释放量均与热解温度和煤中氮的赋存形态有关。更多还原

【Abstract】 A systematic study on emissions and control of nitrogen oxide, toxic trace elements and submicrometer particles during coal combustion was conducted. The thermodynamic equilibrium distributions of trace elements during coal combustion was examined. The transformation and concentration of arsenic were conducted on an electrically heated drop tube furnace. Results show that the low of concentration and dispersion of As in different coals is very different, which is related to coal types and furnace temperature. Studies were carried out to examine the effectiveness of sorbents (TiO2, CaCO3 and Ca(OH)2) on As emission control during coal combustion. The results indicate that all three sorbents tested are capable of effectively capturing arsenic, whereas different sorbent has a different capture capacity and the capture mechanisms are different. A systematic study on submicrometer particles generation, evolution and capture in combustion processes was conducted. To better understand the capture characteristics of the submicrometer particles, experiments were carried out using TiO2 CaCO3 and Ca(OH)2 as sorbents. A circumfluent cyclone system was developed to capture submicrometer particles. The experimental study was carried out on the collection efficiency, pressure drop of the system which used air and molecule sieve as test material system. A reliable density functional theory (DFT) method at B3LYP/6-311++G** level was employed to investigate the reaction mechanism of organic nitrogen during coal pyrolysis. Experiments were carried out in a tubular quartz reactor at 400癈~1000癈. With different coal ranks, the concentrations and nitrogen types are different. The formation of HCN and NH3 during coal pyrolysis was studied to discussed in terms of some factors that affect the nitrogen distribution, including temperature, coal rank and petrographic composition of coal. It indicates that the concentrations of HCN and NH3 are increasing with increasing temperature. Coal rank and petrographic composition are important factors influencing the formation of HCN and NH3 during pyrolysis.更多还原