NIRS-XRF联用的煤炭发热量高稳定检测

Highly stable analysis of coal calorific value using combined NIRS-XRF

实时获知煤炭发热量对于及时调整电站锅炉风粉配比和提高煤炭燃烧效率具有重要意义,为了实现电力生产中发热量的稳定快速检测,提出了一种近红外光谱(Near Infrared Spectroscopy, NIRS)与X射线荧光光谱(X-ray Fluorescence, XRF)联用的煤炭发热量高稳定检测方法,它结合了NIRS能高稳定检测煤中与发热量正相关的有机基团的优势与XRF能高稳定检测与发热量负相关的成灰元素的特点,大大提高了对煤炭发热量的测量重复性。在光谱预处理中,先将两套光谱融合作为偏最小二乘回归的输入变量进行全谱初步建模,依据回归系数选择NIRS光谱中的有效波段,再将它与XRF光谱中的成灰元素谱线一并融合进行归一化处理。建模时将预处理后的融合光谱数据作为输入变量,利用偏最小二乘回归对煤炭发热量进行建模。实验结果表明,NIRS-XRF联用方法对定标集煤样发热量预测的线性相关度系数(R^(2))为0.995,对验证集煤样发热量预测的最小均方根误差、平均相对误差和标准偏差分别为0.24 MJ/kg,0.61%和0.05 MJ/kg,测量重复性满足小于0.12 MJ/kg的国家标准。NIRS-XRF联用的煤炭发热量高稳定检测方法有望推广应用于火力发电、煤化工、冶金、水泥和焦化等“高碳”行业,助力我国按期实现碳中和目标。

It is important to know the calorific value of coal in real time for adjusting the ratio of air to pow-der of power plant boilers and increasing the coal combustion efficiency.Currently,power production is in urgent need of a rapid,highly stable calorific-value detection method.Therefore,this paper innovatively proposes a highly stable detection method for the coal calorific value using the combination of near-infrared spectroscopy(NIRS)and X-ray fluorescence(XRF)spectroscopy,which significantly improves the mea-surement repeatability of the coal calorific value by combining the advantages of NIRS for highly stable de-tection of organic groups positively related to the calorific value in coal and XRF spectroscopy for ash-form-ing elements negatively related to the calorific value.The spectral preprocessing method used in this study involves fusing the two sets of spectra as input variables for partial least squares regression(PLSR)for preliminary modeling of the full spectrum,selecting the effective bands in the NIRS spectrum according to the regression coefficients,and then fusing them with the ash-forming element XRF spectra for normaliza-tion.All the data of the preprocessed fused spectra are used as input variables to model the coal calorific value using PLSR.The experimental results indicated that the linear correlation coefficient(R^(2))of the present NIRS-XRF coupled method for the prediction of the calorific value of the calibration set coal sam-ples was 0.995,and the minimum root-mean-square error,average relative error,and standard deviation for the prediction of the calorific values of the validation-set coal samples were 0.24 MJ/kg,0.61%,and 0.05 MJ/kg,respectively.The measurement repeatability fully satisfied the requirement of<0.12 MJ/kg based on the national standard.The proposed highly stable detection method combining NIRS and XRF spectroscopy for the coal calorific value is expected to be popularized and applied in high carbon industries such as thermal power generation,the coal chemical industry,metallurgy,cement,coking,etc.,to help China achieve carbon neutrality on schedule.