摘要
经脱硫脱水处理后的天然气组分包括甲烷、乙烷、丙烷、二氧化碳、氮气、氢气、一氧化碳以及C_4以上(记为C_4^+)的未知烷烃成分等物质,其中前7种组分为天然气中的主要组分,占天然气含量的90%以上。在运用已有的拉曼光谱分析方法对天然气成分进行分析时,少量的C_4^+未知烷烃组分会对结果造成较大的影响。本研究提出了一种新的拉曼分析方法,由拉曼光谱自动分解算法和定量分析模型组成。首先,基于拉曼光谱的线型叠加性,利用非线性最小二乘法将天然气拉曼光谱分解为7种纯物质组分的拉曼光谱分量和若干个洛伦兹谱峰之和的形式,其中C_4^+未知烷烃成分的含量是用各种烷烃分子共有的CH变形振动峰反映。然后,利用训练样本来建立其它物质相对于甲烷的特征峰面积和对应的浓度之间的模型。相比于已有的拉曼分析方法,本算法克服了含有C_4^+未知烷烃成分的天然气组分的检测难题,且具有较好的稳定性和准确性。实验结果表明,此方法对甲烷、乙烷、丙烷、二氧化碳、氮气、氢气和一氧化碳的最大绝对测量误差分别为0.57%、0.37%、0.21%、0.07%、0.18%、0.04%和0.13%;与气相色谱检测结果的相关系数也分别达到了0.997、0.986、0.991、0.998、0.993、1.000、0.995和0.982。
After desulfurization and dehydration treatment,natural gas is composed of methane,ethane,propane,carbon dioxide,nitrogen,hydrogen,carbon monoxide and unknown alkane components of C 4 or more(denoted as C 4+).The sum of the content of first seven components is more than 90%of natural gas.When the existing Raman spectral analysis methods are applied to analyze the natural gas composition,a small amount of unknown alkane components C 4+will have a greater impact on the analysis precision.On the basis of this,a novel Raman analysis method which consists of a spectral automatic decomposition algorithm and a quantitative analysis model has been developed.Based on a linear additivity of Raman spectra,the Raman spectrum of a natural gas sample can be decomposed into the sum of the Raman spectra of pure constituents and several Lorentz peaks by a nonlinear least-square optimization algorithm.The content of the unknown alkane component C 4+can be described as the area of C H deformation vibration peak common for most alkane molecules.Samples of the training set are used to establish the model between Raman characteristic peak area and corresponding concentration for each component relative to methane.Compared with the existing Raman analysis methods,the new method solves the issue of analyzing natural gas containing unknown alkane components and has good stability and accuracy.Experiments show that the maximum absolute errors of this algorithm for methane,ethane,propane,carbon dioxide,nitrogen,hydrogen,and carbon monoxide respectively reach 0.57%,0.37%,0.21%,0.07%,0.18%,0.04%,0.13%,and the correlation coefficient of gas chromatographic results also reaches 0.997,0.986,0.991,0.998,0.993,1.000,0.995,0.982,respectively.
作者
高颖
戴连奎
朱华东
陈昀亮
周理
GAO Ying;DAI Lian-Kui;ZHU Hua-Dong;CHEN Yun-Liang;ZHOU Li(College of Control Science and Engineering,Zhejiang University,Hangzhou 310027,China;Research Institute of Natural Gas Technology,PetroChina Southwest Oil&Gasfield Company,Chengdu 610213,China)
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2019年第1期67-76,191-192,共11页
Chinese Journal of Analytical Chemistry
基金
国家自然科学基金项目(No.U1609213)资助~~
关键词
天然气
拉曼光谱
洛伦兹谱峰
非线性最小二乘法
光谱分解
Natural gas
Raman spectroscopy
Lorentz peak
Nonlinear least square
Spectral decomposition
