Oxidation Characteristics & Kinetic Parameters Of Bituminous Coal Spontaneous Combustion At Low Temperature In Lean-oxygen Ambient

Coal fire is one of the most serious disasters in coal production of China.And coal fires originate from coal spontaneous combustion caused by oxidation starting even at low temperatures.It also makes the oxygen poor environment has become an important factor in the early development of the coal fire face.To prevent the occurrence of fire,the focus should be placed on the low temperature oxidation of coal oxidation in early stage,At the same time,the poor oxygen also makes the oxidation of coal is different from the typical characteristics of oxidation in the air environment,Aiming at the particularity and sign of low temperature oxidation of coal caused by oxygen poor environment,the related experimental study was carried out,and focus on lean oxygen caused by coal low temperature oxidation index and influence of gas concentration difference,temperature programmed process（temperature characteristic curve,heating rate,temperature difference curve and cross point temperature）,analysis of oxidation kinetics theory,empirical research combined with thermogravimetry and infrared microscopic,and the mechanism of specific effects of poor oxygen generation and system the development of fire.This paper selects the Bulianta mine of Shendong mining area of coal sample to carry out a series of temperature programmed experiments,TG/TG and FTIR test.The coal crushing and screening for 0.2⁰.3mm,0.3⁰.45mm,0.45⁰.6mm,6⁰.9mm four different particle size to use,take the oxygen concentration were 21%,18%,14%,10.5%,5%,3%of the dry air as the experimental gas.Through the low temperature oxidation temperature programmed experiments carried out with different particle size of coal sample under different oxygen concentration index of gas generated variation characteristics and temperature experiments show that the oxygen concentration and particle size on the index of bituminous coal low temperature oxidation process of gas concentration and temperature characteristics of the obvious effect,higher oxygen concentration and the smaller the particle size,the corresponding index the gas yield is high,the heating rate is higher,the cross point temperature（CPT）is low.But in the process of oxygen concentration on the index of gas concentration increases with increasing temperature.The regularity of influence,the temperature variation of gas concentration index curve trend of each other between hydrocarbon indicators（C₂H₄,C₂H₆,C₃H₈ and gas）and CO index were in the coal gas reaches a certain temperature starting from the trace release stage to accelerate release the same size of coal gas production between the index with the oxygen concentration variation showed good regularity,the same rule also exists in different sizes.Through theoretical analysis combined with experimental results,the energy conservation equation is established and calculated the kinetic parameters and apparent activation energy Ea and pre exponential factor A₀ by temperature characteristic curve and export oxygen concentration curve,oxygen reaction enthalpyΔH_O2 calculation unit quality,The dimensionless parameter B of the normalized maximum heat release rate at the stage of low temperature oxidation of coal spontaneous combustion was proposed,and the relationship between the B(B=（?）Y_O2⁰ΔH_O2/αMC_p) value and the important parameter CPT in the process of low temperature oxidation was analyzed,B>1,CPT can be achieved,the temperature cross,otherwise it is not.By thermogravimetry oxygen poor（lower than the normal oxygen content of air）effect on coal pyrolysis characteristics of temperature and activity,the maximum weight loss rate of temperature and oxygen poor degree has a certain regularity,poor oxygen reactivity has inhibitory effect on coal pyrolysis.Show that the FTIR experiment,coal methyl,methylene and-CH absorption peak intensity at 150℃will decrease with temperature increasing,in this process,the higher the concentration of oxygen is corresponding methyl,methylene and-CH attenuation increases with peak intensity,index of oxidation of hydrocarbon gas from methyl,methylene and-CH in coal analysis.From the micro perspective and the macro indicators of the oxygen concentration of coal oxidation mechanism.