摘要
预热燃烧技术是将燃料改性后再燃烧的一种高效清洁燃烧技术。将该技术应用于回转窑燃烧有助于降低单位产品燃料消耗,且该技术具有燃料适应性广和NO_(x)排放低等优点。与煤粉相比,预热燃料的燃烧特性具有显著差异,导致传统煤粉燃烧器的设计参数并不适用于高温预热燃料。因此,需要针对高温预热燃料用回转窑燃烧器开展系统研究,其中旋流数作为燃烧器设计中的关键参数,对火焰特性具有显著影响。利用Fluent软件,比较预热燃料燃烧与常规煤粉燃烧的具体差异,并模拟不同旋流数下预热燃料在回转窑内的燃烧过程,探究旋流数对流动特性、温度分布、组分分布和NO_(x)分布的影响规律。结果表明:相比于传统煤粉燃烧,高温预热燃料燃烧速率快、火焰紧凑、高温区域集中,且排放烟气中NO_(x)含量显著降低。旋流数增大对改善预热燃料的燃烧性能具有显著效果。随着旋流数的增大,燃烧器出口区域出现中心回流区,且回流效果逐渐增强;火焰形状逐渐变粗和变短,当超过一定限值时,火焰开始发散;当旋流数在一定范围内,窑尾出口烟气中的CO浓度和NO_(x)浓度随着旋流数的增大而逐渐降低。在综合考虑火焰长宽度、污染物排放等特性的基础上,对于所研究的结构,在轴向动量一定的情况下,旋流数在0.2~0.8以内燃烧性能最佳。
Preheating combustion technology is an efficient and clean combustion technique that involves modifying the fuel before combustion.Applying this technology to the combustion in a rotary kiln helps to reduce the fuel consumption per unit product and offers advantages such as wide fuel adaptability and low NO_(x) emissions.Compared with coal powder,the combustion characteristics of preheated fuel are significantly different,making the design parameters of traditional coal powder burners unsuitable for high-temperature preheated fuel.Therefore,systematic research is needed for the design of rotary kiln burners for high-temperature preheated fuel,where the swirl number is a key parameter in the design of the burner and has a significant impact on flame characteristics.Fluent software is used to compare the specific differences between preheated fuel combustion and conventional coal powder combustion,simulate the combustion process of preheated fuel in the rotary kiln under different swirl numbers,and explore the impact of the swirl number on flow characteristics,temperature distribution,component distribution,and NO_(x) distribution.The results show that compared with traditional coal powder combustion,the combustion rate of high-temperature preheated fuel is fast,the flame is compact,the high-temperature area is concentrated,and the NO_(x) content in the emitted flue gas is significantly reduced.Increasing the swirl number has a significant effect on improving the combustion performance of preheated fuel.With the increase of the swirl number,a central recirculation zone appears in the burner outlet area,and the recirculation effect gradually strengthens;the flame shape gradually becomes thicker and shorter,and when it exceeds a certain limit,the flame begins to diverge.When the swirl number is within a certain range,the CO concentration and NO_(x) concentration in the flue gas gradually decrease as the cyclone number increases.Based on a comprehensive consideration of flame length and width,pollutant emissions,and other characteristics,for the structure studied in this paper,the combustion performance is best when the swirl number is between 0.3 and 0.8 under the condition of a certain axial momentum.
作者
丁雨晨
王俊杰
蔡军
朱治平
DING Yuchen;WANG Junjie;CAI Jun;ZHU Zhiping(State Key Laboratory of Coal Conversion,Institute of Engineering Thermophysics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Shanxi Engineering Research Center of Coal Clean,Efficient Combustion and Gasification,Datong 037305,China)
出处
《洁净煤技术》
北大核心
2025年第S1期416-425,共10页
Clean Coal Technology
基金
国家重点研发计划“战略性科技创新合作”专项资助项目(2022YFE0206600)
关键词
多通道燃烧器
旋流数
预热燃烧
回转窑
数值模拟
multi-channel burner
swirl number
preheating combustion
rotary kiln
numerical simulation
作者简介
丁雨晨(2000—),女,江苏徐州人,硕士研究生。E-mail:dingyuchen@iet.cn;通讯作者:朱治平(1979—),男,湖北恩施人,研究员。E-mail:zhuzhiping@iet.cn。
