Research On Coal Quality Analysis Technology Based On XRF-assisted LIBS

Quickly obtaining the content of various elements and industrial indicators of coal entering the plant and the coal entering the furnace are of great significance for the optimal control of coal blending and combustion in thermal power generation.However,there is currently no method for comprehensive analysis of coal’s calorific value,industrial indicators(ash,volatile and sulfur)and various elements contained in coal.Laser-Induced Breakdown Spectroscopy(LIBS),as an emerging spectroscopy method,is one of the most potential coal analysis techniques due to its rapid,safe,non-radiation,and simultaneous measurement of multiple elements.Due to the Rayleigh-Taylor instability(RTI),the LIBS measurement results are unstable.While X-ray fluorescence spectroscopy(XRF)has good results for the measurement stability of coal quality,X-ray fluorescence cannot measure light elements such as C and H in coal.Therefore,combining the advantages of XRF’s highly stable measurement of ash-forming elements in coal with the characteristics of LIBS’s ability to perform all-element analysis on samples to form a set of XRF-assisted LIBS coal comprehensive index detection technology,not only can detect organic elements,and it can detect inorganic elements with high stability.After principal component analysis(PCA),the obtained spectrum is analyzed by partial least squares(PLS)to model the calorific value,industrial indicators and various elements in coal.Based on the above ideas,this paper combines the XRF spectrum and LIBS spectrum of multiple sets of coal samples for modeling and predictive analysis.This article first introduces the current status of coal quality analysis,the research status of LIBS used in coal quality analysis,and the principle and characteristics of LIBS.Then it introduces the research development of XRF for coal quality analysis and the principle of XRF.An experimental device for XRF-assisted LIBS for coal quality analysis was built.The measurement stability of the experimental device was optimized by calibrating the LIBS spectrum and XRF spectrum,and the data preprocessing was performed on the LIBS spectrum and XRF spectrum.Combine the processed LIBS spectrum and XRF spectrum to model and analyze the calorific value,ash content,volatile content,sulfur content and various elements in the coal.And carried out industrial site debugging.Innovations in this article:Technological innovation: Combining the advantages of XRF measurement of inorganic elements and the characteristics of LIBS measurement of all elements,a method of XRFassisted LIBS measurement of coal quality is proposed.This method can not only accurately measure the calorific value of coal and other indicators,but also ensure that these indicators are measured repeatedly.Method innovation: The Cu line in the XRF spectrum is used to calibrate its spectrum;the PCA analysis and PLS modeling are used to model and analyze coal calorific value and other indicators.The thesis is divided into the following parts based on the above content:1.Introduced the research status of LIBS and XRF on coal analysis,and elaborated the measurement principle of LIBS and XRF in detail.The principle of principal component analysis and partial least squares method is introduced,and the coefficient of determination(R2),root mean square error(RMSE),relative standard deviation(RSD)and standard deviation(SD)of the calibration curve are introduced to compare the established the model is evaluated.2.The experimental device of XRF assisted LIBS is introduced.The Cu wire in the XRF spectrum is introduced to calibrate the XRF spectrum to eliminate the influence of temperature and environment on the XRF device.3.The spectral line preprocessing of LIBS spectrum and XRF spectrum is introduced,and the modeling spectral line is selected by calculating the RSD of the measured intensity of each element in each spectrum.4.Compare the prediction results of coal calorific value by XRF-assisted LIBS and single LIBS method.Calculated XRF assisted LIBS analysis and prediction of coal industry indicators and various elements.Based on this method,a set of XRF-assisted LIBS coal quality analyzer was developed for the experimental measurement of coal entering the plant and coal entering the furnace of the power plant.Compared with the traditional chemical method,this method obtains better prediction results.