基于Langmuir-Hinshelwood动力学解析O2/CO2/H2O气氛下烟煤焦反应机理  

Langmuir-Hinshelwood kinetic model study of bituminous coal char reaction mechanism in O_2/CO_2/H_2O atmosphere

作　　者：卜昌盛 王文康 韩启杰 王昕晔 张居兵[1] 陈丹丹[1] 朴桂林[1] 蒋勇 BU Changsheng;WANG Wenkang;HAN Qijie;WANG Xinye;ZHANG Jubing;CHEN Dandan;PIAO Guilin;JIANG Yong(Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control,School of Energy&Mechanical Engineering,Nanjing Normal University,Nanjing210042,Jiangsu,China;Zhongan Joint Coalification Co.,Ltd.,Huainan232089,Anhui,China)

机构地区：[1]南京师范大学能源与机械工程学院,江苏省物质循环与污染控制重点实验室,江苏南京210042 [2]中安联合煤化有限责任公司,安徽淮南232089

出　　处：《化工学报》2018年第12期5301-5308,共8页CIESC Journal

基　　金：国家自然科学基金青年基金项目(51606104);安徽省科技重大专项计划项目(15czz02045);江苏省“六大人才高峰”高层次人才(XNY-034); 江苏省高校自然科学研究面上项目(16KJB470010);江苏省研究生科研创新计划(KYCX18_1232).

摘　　要：流化床富氧燃烧湿烟气循环兼具经济与环保优势。湿烟气循环(O_2/CO_2/H_2O)条件下煤焦与O_2、CO_2及H_2O的反应同时发生。为探究O_2/CO_2/H_2O气氛下煤焦-O_2、煤焦-CO_2、煤焦-H_2O反应间的相互作用机制,在自制高精度热重实验装置上系统考察了O_2、CO_2、H_2O及其混合气氛下,典型烟煤焦在900℃的反应特性。基于吸附和脱附原理的Langmuir-Hinshelwood (L-H)机理性模型分别计算了烟煤焦与O_2、CO_2和H_2O反应的动力学参数。通过采用单独活性位点与竞争活性位点两种假设分析了O_2/CO_2、O_2/H_2O和CO_2/H_2O气氛下烟煤焦-O_2、烟煤焦-CO_2和烟煤焦-H_2O两两反应间的作用机制,揭示了H_2O分子优先吸附于烟煤焦表面活性位点,O_2分子次之,而CO_2分子相对滞后。O_2/CO_2/H_2O气氛下烟煤焦-O_2、烟煤焦-CO_2、烟煤焦-H_2O反应表现出部分竞争反应活性位点,传统的单独活性位点与竞争活性位点假设均无法准确描述其反应速率特性。基于H_2O分子优先,O_2分子次优先吸附的原理,建立了O_2、CO_2、H_2O混合气氛下煤焦反应速率L-H动力学方程,方程计算结果与实验值良好吻合。研究结果为深入分析煤焦颗粒流化床富氧燃烧特性及构建可靠、准确的燃烧反应模型提供了理论支撑。Wet-recycle oxy-fuel(O2/CO2/H2O)fluidized bed(FB)combustion shows high efficiency of the power plant and low emission of pollutants.In O2/CO2/H2O atmosphere,char-O2,char-CO2and char-H2O reactions can occur at the same time.To reveal the mechanism of interaction among those reactions,macro-thermogravimetric analysis(TGA)experiments were carried out in mixture of O2,CO2and H2O at temperature of900℃using a bituminous coal-char.The reaction kinetics of char-O2,char-CO2and char-H2O reactions were obtained through Langmuir-Hinshelwood(LH)model fitting.Assumptions of separate active sites and common active sites were used to analyze the experimental data in O2/CO2,O2/H2O and CO2/H2O atmospheres,results show that H2O molecules have priority in taking active sites,following by O2,and finally is CO2.In O2/CO2/H2O atmosphere,partial competition among char-O2,char-CO2and char-H2O reactions was experimentally observed,and neither conventional separate active sites nor common active sites models could describe the reaction rate of bituminous char.According to the theory of H2O molecules primarily and O2molecules sub-primarily occupy active sites when O2,CO2and H2O are present,a new L-H type model was built.The developed model was found to describe well with the measured reaction rate of bituminous char in mixture of O2,CO2,and H2O.The results of this work provide theoretical basis for analyzing of the oxy-fuel FB combustion characteristics of char and developing of reliable char combustion model.

关 键 词：Langmuir-Hinshelwood模型 O2/CO2/H2O 煤焦 动力学 

分 类 号：TQ534[化学工程—煤化学工程]