Study On Heat Production Law Of Suntuan 1/3 Coking Coal In Low Temperature Oxidation Process

Coal spontaneous combustion disaster is one of the main disasters affecting coal mine safety production.Low temperature oxidation heat production of coal is the key process of coal spontaneous combustion.In order to study the heat production characteristics of the low temperature oxidation process of coal,this paper takes 1/3coking coal of 7 coal seam in Suntuan Mine as the object,studies the segmentation characteristics and influencing factors of mass change caused by coal heat generation process on a macro level,and the total heat release and heat production at different stages of the low temperature oxidation process of coal and its influencing factors are analyzed,and explores the evolution process of functional groups causing coal oxidation heat production in coal.The gaseous products of different heat production stages were analyzed,and the factors and heat production models of different heat production stages in the low temperature oxidation process of coal were established.The activation energy of each heat production stage under different influencing factors was calculated to judge the difficulty of heat production process.The research results are of great significance to the coal mine to put forward fire prevention and extinguishing measures.Through thermogravimetric analyzer,the segmented characteristics of low temperature oxidation of coal under different particle sizes,different heating rates and different oxygen concentrations were tested and analyzed.It was found that the segmented transition temperature of different stages of coal decreased with the decrease of particle size,increased with the increase of heating rate,and increased with the decrease of oxygen concentration.The low temperature oxidation heat production characteristics of coal under different particle size,heating rate and oxygen concentration were studied by differential scanning calorimeter.It is found that the main sources of heat production in low temperature oxidation of coal are evaporation desorption stage and oxygen absorption weight gain stage.The heat production in evaporation desorption stage increases with the increase of particle size and heating rate.The heat production in the oxygen absorption weight gain stage increases with the increase of particle size,heating rate and oxygen concentration.The temperature-programmed oxidation device was used to prepare coal samples with different oxidation degrees in the low-temperature oxidation process of coal.The temperature-programmed oxidation and Fourier transform infrared spectroscopy tests were carried out.It was found that the functional groups in the low-temperature oxidation process of coal showed a sharp decrease in the hydroxyl content in the evaporation desorption stage,and a sharp decrease in the aliphatic hydrocarbon content in the oxygen absorption weight gain stage.In this process,CO,CO₂,C₂H₄,C₂H₆ and C₃H₈ gases were generated.Through the analysis of TG-DSC experimental results,the heat generation model of evaporation desorption and oxygen absorption weight gain stage of coal under different particle sizes,different heating rates and different oxygen concentrations was established and the change of activation energy was analyzed.It was found that the activation energy decreased with the decrease of particle size,the increase of heating rate and the increase of oxygen concentration.