PX装置吸附塔进料非芳含量的拉曼定量分析  

Quantitative Analysis for Non-aromatic Hydrocarbon in the Feedstock of an Adsorption Tower in a P-Xylene Unit Based on Raman Spectroscopy

作　　者：蒋飘逸 戴连奎[1] JIANG Piaoyi;DAI Liankui(College of Control Science and Engineering, Zhejiang University, Hangzhou 310027,China)

机构地区：[1]浙江大学工业控制技术国家重点实验室,浙江杭州310027

出　　处：《光散射学报》2020年第3期237-244,共8页The Journal of Light Scattering

基　　金：国家自然科学基金项目(No.U1609213)。

摘　　要：对二甲苯吸附塔进料液主要由乙苯(EB)、对二甲苯(PX)、间二甲苯(MX)、邻二甲苯(OX)和其它非芳烃组分(记为NA)构成,其中NA占3~10%左右。然而,由于NA本身是一类烷烃类混合物,具体构成未知,所以是进料液在线分析中的难点。为此,本文提出了一种基于分段拉曼光谱分解的进料液成分分析方法。针对对象特性,选取两段特征光谱。对于特征谱段650~900 cm^-1,认为NA光谱分量可忽略,基于直接光谱分析算法分解得到了四种主要芳烃组分的峰面积;而在1350~1550 cm^-1段,NA光谱分量较大,本文引入结合洛伦兹函数的拉曼光谱自动分解算法,可分解得到用洛伦兹谱峰拟合的NA组分的峰面积。最后,基于训练样品各组分的峰面积和浓度建立光谱定量分析模型。实验结果表明:对于NA含量,标准预测误差为0.242%,复相关系数达到0.993,本方法的预测精度显著高于PLS算法与直接光谱分解法,富有实际应用价值。The feedstock in an adsorption tower in a p-xylene unit is mainly composed of ethylbenzene(EB),p-xylene(PX),m-xylene(MX),o-xylene(OX)and other non-aromatic hydrocarbon components(denoted as NA).The content of NA is about 3~10%of feedstock,which will directly affect the adsorption tower operation and the purity of PX product,so it needs to be detected online quickly.However,NA is a mixture of different alkanes,whose composition is unknown,so it is difficult to analyze NA in the feedstock.Therefore,this paper proposed a novel method based on two spectral decomposition algorithms for two Raman spectral regions.According to the difference of Raman spectra between aromatic components and NA,two characteristic regions are chosen.NA spectral components can be neglected in the region 650~900 cm^-1,so a direct decomposition algorithm is applied to get their corresponding peak areas based on spectra of pure components EB,PX,MX and OX.In the region 1350~1550 cm^-1,another spectral decomposition algorithm based on Lorentzian function is adopted to obtain the spectral peak of NA which is fitted by several Lorentz peaks,then the corresponding peak area is calculated.Finally,the linear models between peak areas and concentrations of each component are built with all training samples.The experimental results show that the standard prediction error for NA is 0.242%,and the correlation coefficient reaches 0.993.This method can provide more precision than PLS and direct spectral decomposition algorithms,so the new method can be widely applied,especially for the mixture composed of several known components and some unknown substances.

关 键 词：拉曼光谱 光谱分解 非芳烃 吸附塔 洛伦兹谱峰 定量分析 

分 类 号：O657.37[理学—分析化学]