Study On Oxygen-Depleted Oxidation Characteristics Of Xinjiang Coal Samples

In this paper,the combination of experimental research and theoretical analysis is used to study the high temperature oxygen-poor oxidative combustion characteristics in the fire area of Zhunnan coalfield in Xinjiang.The coal samples of Xinjiang Liu Huanggou coal mine,Aiweiergou 1930 coal mine and Aiweiergou 2130 coal mine are selected as research objects.The experimental conditions of high temperature oxygen-poor oxidation were established,studying the influence of different oxygen concentration on the characteristic parameters of coal oxidation process.It can provide theoretical guidance for coal seam spontaneous combustion prediction and control of coal field fire area under different oxygen concentrations,and improve the oxygen-poor evolution of coal fire disaster.Process mechanism research provides a basis.Firstly,using industrial analyzers,elemental analyzers,physicochemical adsorption instruments,laser thermal conductivity analyzers,X-ray diffractometers and other experimental equipment to study the coal industrial composition,element content,specific surface area,coal content of coal samples in the fire area of the Zhunnan coalfield in Xinjiang,The basic parameters of coal quality such as pore size distribution,thermal conductivity and microcrystalline structure parameters provide the basis for subsequent analysis.Secondly,the thermogravimetric experiments were carried out to study the oxidative pyrolysis process of coal samples from 30-950? under different oxygen concentrations,and the TG,DTG and DSC curves were analyzed.The coal sample pyrolysis process was divided into three stages(dry degassing Stage,active thermal decomposition stage,heat polycondensation stage);oxidation process is di'vided into five stages(water evaporation and gas desorption weight loss stage,oxygen absorption weight increase stage,thermal decomposition weight loss stage,combustion stage and burnout stage),and it is determined Six characteristic temperature points(high adsorption temperature T1,oxygen absorption weight increase initial temperature T2,oxygen absorption weight maximum temperature T3.ignition point temperature T4,maximum weight loss rate temperature T5,burnout temperature T6).It is concluded that with the decrease of oxygen concentration,the characteristic temperature point of coal sample oxidation increases,the maximum exothermic temperature point of coal sample increases gradually,the maximum exothermic power decreases gradually,and the total reaction process of coal sample The calorific value is reduced,the coal-oxygen reaction exhibits hysteresis,and the hysteresis effect is obvious when the oxygen concentration is 3%.Secondly,infrared spectroscopy was used to test the functional group of coal samples after high temperature and oxygen-poor treatment,and the change rule of main functional groups in coal was obtained:the content of aliphatic hydrocarbons,aromatic hydrocarbons and oxygen-containing functional groups in coal samples was the highest at T2 temperature point.As the treatment temperature increases,the content decreases;the oxygen concentration in the reaction increases,the hydroxyl content decreases,and the content of aliphatic hydrocarbons and oxygen-containing functional groups increases.Thus,aliphatic hydrocarbons and oxygen-containing functional groups can be used as representative functional groups to characterize the degree of reaction of coal oxygen.Finally,through elemental analysis of the oxygen-treated coal sample,it is found that as the oxygen concentration increases,the O/C element ratio of the coal sample increases,which is proportional to the oxygen-containing functional group of the coal sample,and O/C is also obtained.The element ratio is an important parameter that reflects the content of oxygen-containing functional groups in coal samples.