火焰发射光谱对K元素激光诱导击穿光谱测量的影响  

Influence of Flame Emission Spectroscopy on K measurement Using Laser Induced Breakdown Spectroscopy

作　　者：张志昊[1] 宋蔷[1] Zeyad T.Alwahabi 姚强[1] 

机构地区：[1]清华大学热科学与动力工程教育部重点实验室,北京100084 [2]School of Chemical Engineering,University of Adelaide

出　　处：《光谱学与光谱分析》2015年第4期1033-1036,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(51076072);国家重点基础研究发展(973)计划项目(2013CB228500)资助

摘　　要：在煤和生物质燃烧过程中,燃料中的碱金属元素会发生气态释放,并在随烟气降温的过程中凝结,产生热力设备结渣、腐蚀、积灰等问题,影响设备的安全运行。激光诱导击穿光谱（LIBS）技术是测量煤/生物质火焰中碱金属元素分布的有效手段。建立了一套火焰场内K元素的LIBS测量系统,分别测量了不同ICCD门宽时间条件下火焰场内K元素的火焰发射光谱（FES）信号和LIBS信号,并计算、比较了二者的信号强度随测量系统ICCD门宽时间变化的规律。实验结果表明,相同ICCD门宽时间条件下,火焰场内K元素LIBS信号强度显著高于FES信号强度。随着ICCD门宽时间的增加,二者的信号强度均逐步增加,但是二者的增速变化规律并不相同：K元素LIBS信号强度的增加速度呈现出先快后慢的变化规律;K元素FES信号强度则呈现出线性增加的规律。同时,相同ICCD门宽时间条件下,K元素LIBS信号强度与FES信号强度的比值在ICCD门宽时间为0~8μs的范围内迅速升高至约4;之后,随着ICCD门宽时间的增加,该比值缓慢下降并逐步趋近于1。通过分析火焰场内K元素FES对LIBS测量影响的原理,提出了合理选取LIBS测量系统ICCD门宽时间,使得K元素LIBS信号强度与FES信号强度的比值最大化,从而降低K元素FES对LIBS测量影响,优化了提高火焰场内K元素LIBS信号测量准确度的方法。During the combustion of coal or biomass ,the inherent alkali metals in the fuel will be released to the gas phase .The released alkali species condensed during the cooling of the flue gas ,which may subsequently cause problems with ash deposition and corrosion in thermal fuel conversion systems .Laser Induced Breakdown Spectroscopy （LIBS） is an effective technique to measure the alkali species in the plume of burning coal or biomass .In this study ,an LIBS experimental system with a flat flame burner was set up ,and the Flame Emission Spectroscopy （FES） and LIBS of K in the flat flame environment were measured using different ICCD gate‐width times .The experimental results revealed that with the same ICCD gate‐width time ,the LIBS in‐tensity of K was higher than the FES intensity of K in the flat flame .With the increase of the ICCD gate‐width time ,both inten‐sities increased ,but their increase rates were different ：the increase rate of the LIBS intensity of K was firstly fast then became slow ,but the increase rate of the FES intensity of K was constant .Furthermore ,the intensity ratio of LIBS to FES of K in‐creased monotonically with the ICCD gate‐width time in the range of 0~8μs ,until reaching approximately 4 .Then ,further in‐creasing the ICCD gate‐width time ,such ratio decreased slowly with an asymptote value of 1 .After analyzing the influences of the FES on the LIBS measurement of K in a flame condition ,it is proposed that to minimize such influence ,the optimization of the ICCD gate‐width time was necessary ,which maximized the intensity ratio of LIBS to FES of K and facilitated the measure‐ment accuracy of K in the flame environment using LIBS .

关 键 词：火焰场 碱金属 火焰发射光谱 激光诱导击穿光谱 

分 类 号：O657.3[理学—分析化学]