Investigation On Plasma Characteristics And Test Method For Coal And Ash Based On Laser-induced Breakdown Spectroscopy

In the coal-fired power plants,the measurement of the carbon content of fly ash is an important basis for operation adjustment.At the same time,it also contributes to the economic operation of power plant and reduces pollutant emissions.Due to the influence factors of coal types,boiler structure,operation level and so on,the relationship between various factors is very complex,so it is difficult to directly measure online.The technology of Laser induced breakdown spectroscopy?LIBS?rapidly replace the traditional measuring method of fly ash,and is used in the operation detection of coal-fired power plants,because of its advantages of fast response,high sensitivity,real-time and non-contact measurement etc.This technology is a new analysis method in spectral analysis field.Use high energy laser light source,then form high intensity laser spot?plasma?in analysis material surface.The sample is excited and product light,which is analyzed through the spectrum analysis system and detection system.But the technology still has some defects of measurement needs to solve.In this paper,the plasma characteristics of pulverized coal samples and the detection methods of ash content in laser induced breakdown spectroscopy are studied.23 kinds of pulverized coal samples from different power plants in Shunde of Foshan were used as experimental objects,and the experimental method was used.Detection of Dry Ash Content in Pulverized Coal by Laser-induced Breakdown Spectroscopy.Firstly,the experimental conditions of pretreatment of pulverized coal samples were optimized.Finally,the experimental conditions of binder and pulverized coal were 2:3,the tabletting time was 4mins and the pressure was 20MPa.On this basis,some elements of pulverized coal were selected as the characteristic spectral elements,and the time characteristics of different pulverized coal samples were analyzed.Under the specific delay conditions,the linear relationship between the plasma temperature and the ash content is compared and analyzed.Then,20 kinds of pulverized coal samples were used to analyze the ash content of dry samples of coal samples,and the regression model R² was 0.93.Finally,three kinds of ash samples with unknown ash content were brought into the model to predict their respective ash contents,and the predicted values were compared with the corresponding ash content reference values.The regression model was evaluated and finally reached by using LIBS system to detect pulverized coal Ash content.