摘要
森林可燃物热解的研究,对森林火灾预警和控制具有重要意义。森林可燃物热解过程中主要生成CO、 CO_(2)和CH_(4)等含碳气体,这些气体的不断释放容易引发森林火灾并加剧温室效应,快速准确检测这三种组分的浓度有利于火灾早期预警和大气环境保护。通过频分复用结合可调谐二极管激光吸收光谱(TDLAS)技术准确测量了六种山林树种样品热解气体中CO、 CO_(2)和CH_(4)三种组分的浓度,证明了频分复用-TDLAS技术对森林可燃物热解气体多组分同步测量的适用性。首先,介绍了频分复用-TDLAS技术的基本原理,确定了三种组分互不干扰、且谱线强度适宜的吸收谱线。其次,为了准确反演不同的浓度,对二次谐波(2f)信号和二次谐波/直流(2f/DC)信号的特性进行了研究。通过Simulink仿真的方式,比较了利用2f信号和2f/DC信号反演不同浓度准确性的差异,结果表明2f/DC信号具有更大的线性区间,适用于森林可燃物热解气体中不同浓度组分的测量。最后,利用两支中心波长分别为1 580.0和1 653.7 nm的分布式反馈(DFB)激光器搭建了CO、 CO_(2)和CH_(4)同步测量的实验装置。在900℃管式炉中对六种树种样品进行热解以及热解气体制备,利用Herriott吸收池测量了三种组分的2f/DC信号,通过标准气体建立标定模型获得了热解气体中三种组分的绝对浓度。结果显示,三种组分的2f/DC信号峰值与浓度满足良好的线性关系,线性度大于0.995,且在焦炭气化反应和Boundouard反应的作用下,六种树种样品热解气体中CO浓度明显高于CO_(2)和CH_(4)。通过分析枫香叶样品的光谱,表明在2 s测量时间内,该光谱系统对于CO、 CO_(2)和CH_(4)的最低检测限低于0.008%,灵敏度优于0.005%,满足森林火灾预警的需求。该研究为森林可燃物热解气体多组分同步测量以及森林火灾预警提供了方法参考。
Pyrolysis of forest combustibles is an important research topic in forest fires and is of great significance for early warning and control of forest fires.The pyrolysis of forest combustibles mainly produces carbonaceous gases such as CO,CO_(2),and CH 4.The continuous release of these gases will likely trigger forest fires and aggravate the greenhouse effect.The rapid and accurate detection of the concentrations of these three components is beneficial for early warning of fires and atmospheric environmental protection.In this paper,the concentrations of three CO,CO_(2),and CH 4 components in the pyrolysis gases of six mountain forest tree species samples were accurately measured by frequency division multiplexing combined with tunable diode laser absorption spectroscopy(TDLAS)technique.The applicability of the frequency division multiplexing-TDLAS technique for simultaneous multi-component measurements of pyrolysis gases of forest combustibles is demonstrated.Firstly,the basic principle of the frequency division multiplexing-TDLAS technique is introduced,and the absorption spectra of the three components are determined without interfering with each other and with suitable spectral intensity.Secondly,the characteristics of the second harmonic(2f)signal and the second harmonic/DC(2f/DC)signal are investigated to invert the different concentrations accurately.The difference in the accuracy of inversion of different concentrations using the 2f signal and 2f/DC signal is compared using Simulink simulation,and the results show that the 2f/DC signal has a larger linear interval and is suitable for the measurement of different concentration components in the pyrolysis gas of forest combustibles.Finally,an experimental setup for simultaneous CO,CO_(2),and CH 4 measurements was built using two distributed feedback(DFB)lasers with center wavelengths of 1580.0 and 1653.7 nm,respectively.The 2f/DC signals of the three components were measured using a Herriott absorber cell,and the absolute concentrations of the three components in the pyrolysis gas were obtained by establishing calibration models with standard gases.The results showed that the peak 2f/DC signals of the three components satisfied a good linear relationship with the concentrations withlinearity greater than 0.995,and the concentrations of CO in the pyrolysis gases of the six tree samples were significantly higher than those of CO_(2),and CH 4 under the effect of the coke gasification reaction and Boundouard reaction.by analyzing the spectra of Chinese sweetgum leaf samples,it was shown that within the 2 s measurement time,the spectroscopic system for CO,CO_(2),and CH 4 with a minimum detection limit lower than 0.008%and sensitivity better than 0.005%,which meets the demand of forest fire early warning.This study provides a methodological reference for the simultaneous multi-component measurement of pyrolysis gases of forest combustibles and forest fire early warning.
作者
郭松杰
王璐鹏
陈金铮
马云
梁安
卢志民
姚顺春
GUO Song-jie;WANG Lu-peng;CHEN Jin-zheng;MA Yun;LIANG An;LU Zhi-min;YAO Shun-chun(School of Electric Power Engineering,South China University of Technology,Guangzhou 510640,China;Yunfu Fire and Rescue Detachment,Yunfu 527399,China)
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2024年第3期625-631,共7页
Spectroscopy and Spectral Analysis
基金
国家重点研发计划政府间国际科技创新合作项目(2019YFE0109700)
广东省自然科学基金-杰出青年项目(2021B1515020071)
广东省省级科技计划项目(2020A0505140001)
霍英东教育基金会第十七届高等院校青年教师基金项目(171047)
云浮市科技计划项目(2020020301)资助。
关键词
森林火灾
可燃物热解
TDLAS
频分复用
同步测量
Forest fires
Combustibles pyrolysis
TDLAS
Frequency division multiplexing
Simultaneous measurements
