Research On Mass Concentration Of Particulate Matter In Coalbed Methane Based On Light Scattering Theory

In the context of massive exploitation and utilization of coalbed methane,it is important to ensure the quality of coalbed methane and the safety of the transportation pipeline system.During the exploitation of coalbed methane,solid particles such as pulverized coal,rock chips and mud enter the transportation pipeline with the gas,after separation and filtration,there are still a large number of micron-sized particles in coalbed methane.The walls of the pipeline can be eroded by particles,which can cause serious safety production accidents.Therefore,it is important to analyze and accurately measure the mass concentration of particles in coalbed methane.The light scattering method is widely used in the field of particle measurement due to the advantages of fast measurement speed,high accuracy and real-time measurement.In this paper,the mass concentration of particulate matter is studied based on the Mie scattering theory,and the main work is as follows:（1）Sampling and analysis of particulate matter in coalbed methane pipelines in Linxian and Qinshui,Shanxi Province,the main components of dust particles in coalbed methane in two regions of Shanxi Province are Fe₃O₄、Si O₂、Al₂O₃ and Ca O.Based on the theory of light scattering,the factors affecting the scattering light intensity of particles are analyzed,including the incident light wavelength,particle size,and refractive index.Derive of scattered light intensity and optical power for monodisperse and polydisperse particle populations on single particle Mie scattering theory calculations.（2）Set up a dust particles mass concentration measurement device in the laboratory,use standard dust for experiments,and measure of scattered light intensity of particles in different concentration ranges at multiple scattering angles.The experimental results show that there is a good linear relationship between the mass concentration of dust particles and the output voltage,the linear relationship between particles mass concentration and scattered light intensity was analyzed.The goodness of linear fit R² between the dust concentration and the voltage value at different scattering angles is greater than 0.98 in the concentration range of 0-100 g/m³.The goodness of linear fitR² between dust concentration and voltage value at different scattering angles is greater than 0.95 in the concentration range of 0-10 g/m³ and 0-1 g/m³.By analyzing the relative error,it is concluded that the relative error of the measurement is small when the scattering angle is90°-110°,and stray light has little effect on experimental measurement results.The theoretical and experimental research in this paper provides a reference for the detection of particles mass concentration in coalbed methane.