不同富氧气氛下焦炭氮转化及原位还原的数值模拟  

Numerical Simulation of Char-N Conversion and NO_x In Situ Reduction in Different Oxy-fuel Atmospheres

作　　者：赵红星 郑坤灿 武文斐 ZHAO Hongxing;ZHENG Kuncan;WU Wenfei(School of Energy and Environment,Inner Mongolia University of Science and Technology,014010 Baotou,China;Key Laboratory of High Efficiency and Clean Combustion in Inner Mongolia Autonomous Region,014010 Baotou China)

机构地区：[1]内蒙古科技大学能源与环境学院内蒙古自治区高效洁净燃烧重点实验室

出　　处：《煤炭转化》2020年第1期56-64,共9页Coal Conversion

基　　金：国家自然科学基金资助项目(51866013)

摘　　要：在焦炭燃烧过程中,焦炭颗粒会对产生的氮氧化物起到一定的异相催化还原作用,但其机理仍不明确。基于焦炭颗粒内部有不同碳基和发达的孔隙结构,根据焦炭颗粒在富氧气氛下燃烧的特性,建立了焦炭氮转化的分子动力学模型和多种气体传质模型。使用FORTRAN语言编程模拟了不同富氧气氛下粒径为100μm的单颗粒焦炭的燃尽过程。结果表明:燃烧初期颗粒内部NO出现短暂的积聚现象,颗粒内部的还原能力较弱,随着反应的进行及温度的升高,还原能力增强,由于缺氧而产生了CO气体,有利于NOx的还原。对比了环境温度为1 200℃时,O2和CO2的体积分数比分别为20∶80,25∶75,30∶70的不同气氛下焦炭颗粒内部NO,CO和N2等气体的体积分数,表明O2和CO2的体积分数比为25∶75的气氛是最佳气氛,既保证了焦炭颗粒的高效燃烧,又有利于增强焦炭颗粒的还原能力。In the process of the coke combustion, it is known that coke particles can facilitate the catalytic reduction of nitrogen oxides, but the mechanism is still unclear. Based on the various carbons in coke, developed pore structure and the combustion characteristics of coke particles in oxy-fuel atmosphere, the present study established a molecular dynamics model of char-N conversion and a gas mass transfer model. The combustion process of a single coke particle with a diameter of 100 μm was simulated in different atmospheres. The FORTRAN language was used to program and analyze the results. The results show that a short accumulation of NO in the particles and the reduction ability of the particles are weak at the early stage of combustion. The reduction ability becomes stronger with the progress of the reaction. The CO gas with increasing temperature is produced in the particles due to the lack of the oxygen, which is beneficial to the reduction of nitrogen oxides. Comparing the results obtained in different atmospheres with the volume fraction ratios of O2 to CO2 of 20∶80, 25∶75 and 30∶70 when the ambient temperature is 1 200 ℃, the results show that the volume fraction ratio of 25∶75 is the best one. It not only ensures the efficient combustion of the coke particles, but also enhances the reducing ability of the coke particles.

关 键 词：富氧燃烧 焦炭氮 动力学模型 洁净燃烧 数值模拟 

分 类 号：TK16[动力工程及工程热物理—热能工程]