生物质层燃锅炉低NOx燃烧技术的研究

Study of the Low NO_x Combustion Technology for Biomass-fired Grate Boilers

为解决我国现有生物质层燃锅炉存在NO_x和CO排放量高的问题,建立了生物质床层燃烧和NO_x模型,进行了大颗粒燃料热解特性和焦炭异相反应过程中NO转化的实验研究,得到其动力学参数,并将单元体炉实验结果与模型计算结果进行了对比。针对我国炉型结构特点,提出"之"字形炉拱与空气分级相结合的改进方案。结果表明:现有敞开式炉膛结构所存在的"烟囱流"特点是造成NO_x和CO体积分数高的根源;改进后炉膛内还原区中各气体组分得到充分混合,延长了气体停留时间,从而可以取得炉内控制NO_x质量浓度的显著效果,同时可使CO充分燃尽。

To solve the problems of high NOxand high CO emissions existing in current biomass-fired grate boilers in China,experimental studies were conducted on the pyrolysis characteristics of large fuel particles and the NO conversion behavior during heterogeneous reactions with char by setting up models for both mass combustion and NO xformation,so as to obtain kinetic parameters of above models,and to compare the unit furance experimental data with calculation results.According to the structural features of domestic boilers,an improvement scheme was proposed by adopting the"zigzag " arch combined with air-staged combustion technology.Results show that the"chimney flow" behavior in current open furnaces is found to be the main reason leading to the high concentraions of NOxand CO in flue gas.After improvement,various gas components are well mixed in the reduction zone,and the residence time of the gas mixture is also extended,thus obtaining a clear inhibition effect on NOxconcentration and a complete oxidization of CO.