-
摘要: 本文针对化工过程中在线检测丙烯的需求，研究了基于调制吸收光谱技术（TDLAS）的检测技术，提出了一种独立于光谱线型特征的数值仿真方法，考虑实际激光光源宽线宽对吸光度的影响，通过对比仿真和实验的光谱幅度变化规律，确定了丙烯气体分析装置的设计参数和技术方案，选择中心波长为1 628.5 nm的宽调谐DFB激光器，采用差分方案去除解调光谱的直流偏置，采用多元回归模型降低化工过程的背景气体光谱干扰。在模拟实际环境的气体实验中，该装置在0~1% 量程内的最大相对误差为0.55%。对0.2% 的丙烯进行3小时连续测量，标准差为9.3×10−6；Allen方差分析发现在积分时间为221.9 s 时，极限标准差可达1.33×10−6。在抗干扰测试中，当背景气体甲烷、乙烯的浓度变化时，丙烯的测量误差最大仅为19.17×10−6。调制吸收光谱技术克服了色谱和软测量等传统方法的不足，TDLAS装置可检测有复杂光谱特征的重烃分子，展示了测量精度高、稳定性好、抗背景光谱干扰能力强等优点。
-
关键词:
- 可调谐二极管激光吸收光谱 /
- 丙烯测量 /
- 过程分析 /
- 多元线性回归
Abstract: To satisfy the need for propylene measurement in the olefin production process, Tunable Diode Laser Absorption Spectroscopy (TDLAS) was studied to improve analytical performance. In this paper, a numerical simulation approach is proposed using absorbance from a spectral database to obtain the optimized design parameters, which is independent of spectral features. In the simulation, the effect of a wider linewidth laser on the absorbance profile was considered. Through the comparison of simulation results and experimental collection, the TDLAS-based propylene analysis apparatus was developed correspondingly. It has a 1 628.5 nm center wavelength broad-tuning DFB laser. A differential method was utilized in demodulated spectral acquisition to eliminate bias voltage. The multivariate linear regression model was employed to reduce the strong spectral interference from the background components in the analysis. Based on the simulated field test, the max relative error is 0.55% in the 0~1% range for the step test. For the long-term test, the standard deviation (1σ) is 9.3×10−6 for 0.2% propylene concentration. The best standard deviation is 1.33×10−6 at 221.9 s of integration time through Allen variance analysis. In the anti-interference test, the max error of 19.17×10−6 is demonstrated for 0.2% propylene concentration while methane and ethylene concentrations vary. The disadvantages of traditional methods such as the Gas Chromatogram (GC) and soft measurement methods are overcome by modulated absorption spectroscopy. The TDLAS system for heavy hydrocarbon detection with complex spectral features was demonstrated to have distinct advantages in precision, stability and interference suppression through multivariate regression modeling. -
图 1 数据库中C3H6、CH4、C2H4、C2H6在1 628 nm附近的吸光度
Figure 1. Gas absorbance of C3H6、CH4、C2H4 and C2H6 near 1 628 nm in database
图 2 丙烯光谱的3种线型拟合结果。（a）线型拟合；（b）拟合残差
Figure 2. Fitting results of three line types of propylene spectrum. (a) Absorption profile; (b) fitting residual
图 3 激光器的线宽对丙烯光谱的影响。 （a）线宽对吸光度的影响；（b）线宽对丙烯仿真2f光谱的影响
Figure 3. The influence of laser linewidth on propylene spectrum. (a) Absorbance of propylene; (b) simulation 2f spectra of propylene
图 4 不同调制幅度下C3H6的吸收光谱。（a）数值仿真；（b）实验采集
Figure 4. Absorption spectra of C3H6 with different modulation amplitudes. (a) Numerical simulation; (b) experiment
图 5 不同调制幅度下C3H6的2f光谱峰值强度
Figure 5. 2f spectra intensity of C3H6 at different modulation amplitudes
图 9 分析装置采集到的C3H6、CH4、C2H4吸收光谱和N2背景下光功率变化图
Figure 9. Absorption spectra of C3H6、CH4、C2H4 and optical power in N2 background acquired through the analyzer
图 10 （a）步进测试过程中分析装置丙烯浓度读数曲线；（b）丙烯浓度设定值与分析装置测量值线性关系曲线
Figure 10. (a) Analyzer reading of C3H6 concentration in step test；(b) the linear response of C3H6 analyzer measurement vs. setting gas concentration
图 11 稳定性测试结果。（a）丙烯浓度固定时分析装置浓度读数曲线; （b）Allan方差分析
Figure 11. Stability test results. (a) Analysis device reading curve when propylene concentration is fixed; (b) Allan deviation analysis
图 12 CH4、C2H6背景气体浓度变化情况下装置的C3H6浓度读数
Figure 12. C3H6 concentration reading varying with the concentration of the background gas CH4 and C2H6
表 1 步进测试的丙烯测量精度
Table 1. Measurement error of C3H6 concentration in step test
(×10−6) Setting
concentrationMeasured
concentrationStd.
DeviationAbsolute
error0 −12.12 6.20 12.12 1 000 1 020.09 19.47 20.09 2 000 2 022.57 41.73 22.57 5 000 5 055.13 51.52 55.13 10 000 10 014.32 58.67 14.32 
下载: 导出CSV
表 2 抗干扰测试结果
Table 2. Results of anti-interference test
(10−6) Section Interfering CH4 Interfering C2H6 Measured concentration Std. deviation Absolute error 1 2 000 0 1 997.58 33.96 −2.42 2 1 000 10 2 003.46 33.84 3.46 3 500 100 1 993.64 33.63 −6.36 4 0 300 2 019.17 35.64 19.17
下载: 导出CSV
-
AKAH A, AL-GHRAMI M. Maximizing propylene production via FCC technology[J]. Applied Petrochemical Research, 2015, 5(4): 377-392. doi: 10.1007/s13203-015-0104-3 王振雷, 叶贞成, 钱锋. 丙烯精馏塔智能控制系统设计及应用[J]. 化工学报,2010,61(2):347-351.WANG ZH L, YE ZH CH, QIAN F. Design and implementation of intelligent control system for propylene distillation column[J]. CIESC Journal, 2010, 61(2): 347-351. (in Chinese) ZHANG F, WANG J H, TIAN D L, et al. Research on unregulated emissions from an alcohols-gasoline blend vehicle using FTIR, HPLC and GC-MS measuring methods[J]. SAE International Journal of Engines, 2013, 6(2): 1126-1137. doi: 10.4271/2013-01-1345 KNIGHTON W B, HERNDON S C, FRANKLIN J F, et al. Direct measurement of volatile organic compound emissions from industrial flares using real-time online techniques: Proton transfer reaction mass spectrometry and tunable infrared laser differential absorption spectroscopy[J]. Industrial &Engineering Chemistry Research, 2012, 51(39): 12674-12684. 韩明聪, 董俊国, 彭真, 等. 质子转移反应-飞行时间质谱检测呼出气体中痕量挥发性有机物[J]. 分析化学,2018,46(7):1109-1115. doi: 10.11895/j.issn.0253-3820.171532HAN M C, DONG J G, PENG ZH, et al. Proton transfer reaction time-of-flight mass spectrometry for detection of trace volatile organic compounds in breath[J]. Chinese Journal of Analytical Chemistry, 2018, 46(7): 1109-1115. (in Chinese) doi: 10.11895/j.issn.0253-3820.171532 张强领, 邹雪, 梁渠, 等. 大气挥发性有机物实时在线监测的双极性质子转移反应质谱仪研制[J]. 分析化学,2018,46(4):471-478. doi: 10.11895/j.issn.0253-3820.171234ZHANG Q L, ZOU X, LIANG Q, et al. Development of dipolar proton transfer reaction mass spectrometer for real-time monitoring of volatile organic compounds in ambient air[J]. Chinese Journal of Analytical Chemistry, 2018, 46(4): 471-478. (in Chinese) doi: 10.11895/j.issn.0253-3820.171234 张斌. 基于多神经网络结构的丙烯浓度软测量建模[J]. 计算机与应用化学,2014,31(3):374-376.ZHANG B. Soft sensor modeling for propylene concentration based on MNN[J]. Computers and Applied Chemistry, 2014, 31(3): 374-376. (in Chinese) 齐汝宾, 尹新, 杨立, 等. 多成分有机气体的近红外光谱定量检测方法[J]. 光谱学与光谱分析,2008,28(12):2855-2858. doi: 10.3964/j.issn.1000-0593(2008)12-2855-04QI R B, YIN X, YANG L, et al. Application of NIR spectroscopy to multiple gas components identification[J]. Spectroscopy and Spectral Analysis, 2008, 28(12): 2855-2858. (in Chinese) doi: 10.3964/j.issn.1000-0593(2008)12-2855-04 BENALIOUCHE F, BOUCHEFFA Y, THIBAULT-STARZYK F. In situ FTIR studies of propene adsorption over Ag- and Cu-exchanged Y zeolites[J]. Microporous and Mesoporous Materials, 2012, 147(1): 10-16. doi: 10.1016/j.micromeso.2011.04.040 冯书香, 徐亮, 高闽光, 等. 基于太阳光谱的FTIR技术监测石油化工区丙烯的浓度分布[J]. 红外技术,2012,34(3):168-172.FENG SH X, XU L, GAO M G, et al. Application of Fourier transform infrared spectroscopy based on sun spectrum to monitor the distribution of propylene from petrochemical industry[J]. Infrared Technology, 2012, 34(3): 168-172. (in Chinese) HARWARD SR C N, BAREN R E, PARRISH M E. Determination of molecular parameters for 1, 3-butadiene and propylene using infrared tunable diode laser absorption spectroscopy[J]. Spectrochimica Acta Part A:Molecular and Biomolecular Spectroscopy, 2004, 60(14): 3421-3429. doi: 10.1016/j.saa.2003.11.049 吕晓翠, 李国林, 季文海, 等. 基于特征提取的极限学习机算法在可调谐二极管激光吸收光谱学中的应用[J]. 中国激光,2018,45(9):0911013. doi: 10.3788/CJL201845.0911013LV X C, LI G L, JI W H, et al. Application of feature-extraction-based extreme learning machine algorithm in tunable diode laser absorption spectroscopy[J]. Chinese Journal of Lasers, 2018, 45(9): 0911013. (in Chinese) doi: 10.3788/CJL201845.0911013 朱晓睿, 卢伟业, 饶雨舟, 等. TDLAS直接吸收法测量CO2的基线选择方法[J]. 中国光学,2017,10(4):455-461. doi: 10.3788/co.20171004.0455ZHU X R, LU W Y, RAO Y ZH, et al. Selection of baseline method in TDLAS direct absorption CO2 measurement[J]. Chinese Optics, 2017, 10(4): 455-461. (in Chinese) doi: 10.3788/co.20171004.0455 聂伟, 阚瑞峰, 杨晨光, 等. 可调谐二极管激光吸收光谱技术的应用研究进展[J]. 中国激光,2018,45(9):0911001. doi: 10.3788/CJL201845.0911001NIE W, KAN R F, YANG CH G, et al. Research progress on the application of tunable diode laser absorption spectroscopy[J]. Chinese Journal of Lasers, 2018, 45(9): 0911001. (in Chinese) doi: 10.3788/CJL201845.0911001 LI CH L, GUO X Q, JI W H, et al. Etalon fringe removal of tunable diode laser multi-pass spectroscopy by wavelet transforms[J]. Optical and Quantum Electronics, 2018, 50(7): 275. doi: 10.1007/s11082-018-1539-4 臧益鹏, 聂伟, 许振宇, 等. 基于可调谐二极管激光吸收光谱的痕量水汽测量[J]. 光学学报,2018,38(11):1130004.ZANG Y P, NIE W, XU ZH Y, et al. Measurement of trace water vapor based on tunable diode laser absorption spectroscopy[J]. Acta Optica Sinica, 2018, 38(11): 1130004. (in Chinese) GAO Y W, ZHANG Y J, CHEN D, et al. Laser absorption spectroscopy for detection of hydrogen fluoride using tunable diode laser[J]. Acta Photonica Sinica, 2015, 44(6): 0630003. doi: 10.3788/gzxb20154406.0630003 曹天书. TDLAS气体检测中二次谐波的锁相放大器的研究[D]. 长春: 吉林大学, 2013.CAO T SH. Lock-in amplifier of second harmonic in the TDLAS gas detection[D]. Changchun: Jilin University, 2013. (in Chinese) 刘铭晖, 董作人, 辛国锋, 等. 基于Voigt函数拟合的拉曼光谱谱峰判别方法[J]. 中国激光,2017,44(5):0511003. doi: 10.3788/CJL201744.0511003LIU M H, DONG Z R, XIN G F, et al. Discrimination method of raman spectral peaks based on Voigt function fitting[J]. Chinese Journal of Lasers, 2017, 44(5): 0511003. (in Chinese) doi: 10.3788/CJL201744.0511003 KLUCZYNSKI P, GUSTAFSSON J, LINDBERG Å M, et al. Wavelength modulation absorption spectrometry-an extensive scrutiny of the generation of signals[J]. Spectrochimica Acta Part B:Atomic Spectroscopy, 2001, 56(8): 1277-1354. doi: 10.1016/S0584-8547(01)00248-8 ZHOU X. Diode-laser absorption sensors for combustion control[D]. Stanford: Stanford University, 2005. 谢越, 李飞跃, 范行军, 等. 基于近红外光谱技术的生物炭组分分析[J]. 分析化学,2018,46(4):609-615. doi: 10.11895/j.issn.0253-3820.171084XIE Y, LI F Y, FAN X J, et al. Component analysis of biochar based on near infrared spectroscopy technology[J]. Chinese Journal of Analytical Chemistry, 2018, 46(4): 609-615. (in Chinese) doi: 10.11895/j.issn.0253-3820.171084 ZHENG CH T, YE W L, SANCHEZ N P, et al. Infrared dual-gas CH4/C2H6 sensor using two continuous-wave interband cascade lasers[J]. IEEE Photonics Technology Letters, 2016, 28(21): 2351-2354. doi: 10.1109/LPT.2016.2594028 -
下载:
点击查看大图
计量
- 文章访问数: 4139
- HTML全文浏览量: 995
- PDF下载量: 145
- 被引次数: 0
