焦炭颗粒群氧燃烧速率特性  

Investigation on char cloud burning rates under oxy-combustion

作　　者：刘敬樟[1] 李百航 朱建国[1,2] 李诗媛 劳世奇[1] 

机构地区：[1]中国科学院工程热物理研究所,北京100190 [2]中国科学院大学,北京100049

出　　处：《中国科学：技术科学》2017年第12期1265-1272,共8页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:51406197)资助项目

摘　　要：富氧燃烧技术是一种有效的低碳排放洁净燃烧技术且已受到国内外广泛关注.但其二氧化碳和水分固有的物化本质引发的燃烧和火焰传播等诸多特性有待深入研究.本文仅针对二氧化碳气化对富氧焦炭燃烧速率影响机制进行研究,探讨二氧化碳气化吸热反应、氧气氧化放热反应和富氧交叉竞争反应中二氧化碳气化对焦炭燃烧速率贡献作用和层流火焰传播特性.基于自行搭建的高温富氧燃烧实验平台,研究中高温燃烧环境(1273 K,1773 K)二氧化碳气化对焦炭富氧燃烧速率贡献率和火焰传播特性影响,并与空气燃烧基准工况对比,即27%O_2/CO_2/Ar,27%O_2/Ar,73%CO_2/Ar和21%O_2/N_2/Ar.结果表明:中温燃烧且煤灰非熔融态时气化和氧化反应对焦炭氧燃烧最大燃烧速率贡献率近似相同,分别为47.1%和52.9%.高温富氧燃烧且煤灰熔融态时两者贡献比相差较大,分别为34.8%和65.2%,高温富氧燃烧的焦炭最大燃烧速率高于中温燃烧1.72倍;中温富氧燃烧时颗粒群最大燃烧温度几近相同且略高环境温度27 K,火焰从煤焦外缘传播至焦炭核心.高温富氧燃烧时熔融态颗粒群表面温度略低于环境温度60 K,高于空气燃烧55 K,存在化学发光无火焰锋面.Oxyfuel combustion is an effective low-carbon emission clean combustion technology and many researches focus on this novel technology research and development worldwide. Further investigation is needed on pysicochemical effects of carbon dioxide and gas water on burning rate and oxy-flame propagation, etc. The current research only focuses on the gasification effect of carbon dioxide on char burning rates under oxyfuel combustion, and discussions on the contribution of gasification from carbon dioxide to oxy-char burning rates and flame propagation in three schemes of endothermic gasification reaction from carbon dioxide, exothermic oxidation reaction from oxygen and oxyfuel crossover competing reaction. Compared with air-char combustion, the researches were carried out on oxy-char burning rates and oxy-flame propagation under moderate and high temperatures, i.e., 1273 K and 1773 K, on the novel high temperature oxyfuel combustion experimental rig. Results showed that the gasification from carbon dioxide and the oxidation from oxygen were nearly the same contribution ratio to the oxy-char maximum burning rates under moderate temperature,but this ratio was different under high temperature. In moderate temperature, the coal char maximum burning temperature was almost similar and higher than heating temperature as 27 K, and the flame propagated from outside to inside region. In high temperature,the char burning surface temperature was lower as 60 K and higher than conventional air combustion as 55 K companied with luminescence flameless propagation.

关 键 词：富氧燃烧 焦炭颗粒 气化反应 燃烧速率 火焰传播 

分 类 号：TK16[动力工程及工程热物理—热能工程]