Optimization Of Spontaneous Combustion And Inerting Adsorption Parameters Of Qianyingzi Bituminous Coal

Spontaneous combustion of residual coal in underground goaf is always the main hazard threatening underground safety production.The oxygen adsorption of coal is the root cause of coal spontaneous combustion,choose the inert gases such as CO₂and N₂,fire prevention is to use coal of different gas adsorption to choose difference to prevent coal adsorption on oxygen.At present to prevent spontaneous combustion of coal adsorption research limited to CO₂,N₂ and O₂ on the competitive adsorption of qualitative research,on the best inerting effect parameter optimization is not enough.And research method is not comprehensive,only a single adsorption experiments and molecular simulation,without the combination.Therefore,this paper combines adsorption experiment with molecular simulation,explores the competitive adsorption mechanism of coal on inert gas and O₂ by using bituminous coal samples from Qiyingzi coal mine,obtains the gas concentration ratio of optimal inerting effect,and finally compares the spontaneous combustion effect of coal before and after adsorption.The specific research results are as follows:（1）Based on the theory of spontaneous combustion of coal,a temperature programmed experiment platform was set up to conduct the spontaneous combustion oxidation experiment of coal samples at 0～300℃in the west wing coal pillar working face of Qianyingzi coal Mine.The spontaneous combustion stage of coal samples was divided according to the gas composition and concentration rules detected at each temperature.The oxygen concentration decreased exponentially during the heating process,but the oxygen consumption rate had a sudden rise point at 50～60℃,which proved the end of physical adsorption.The coal sample enters the self-heating stage at110℃and the combustion stage at 260℃.（2）Based on the theory of molecular dynamics and monte carlo method to establish the best bituminous coal molecular Wsier model.The single component adsorption of CO₂,N₂ and O₂ on coal molecules is carried out at the physical adsorption temperature.At the same temperature,the saturated adsorption amount of the three gases is a（CO₂）>a（O₂）>a（N₂）,and the adsorption equilibrium constant b is b（CO₂）>b（N₂）>b（O₂）.The adsorption potential energy,adsorption heat and interaction energy of the system all prove that the adsorption capacity of CO₂ is stronger than that of the other two gases,and the adsorption of CO₂ gas reaches saturation under the pressure of 2.5 MPa.（3）Competitive adsorption of CO₂/O₂,CO₂/N₂ and O₂/N₂ mixtures was carried out in different proportions.When the concentration ratio of CO₂/O₂ was 1:1,the adsorption capacity of the mixed component was the same as that of the single component CO₂ at the same temperature.CO₂/N₂ mixed components concentration ratio of 4:6 with one-component rule is the same,the higher the proportion of CO₂and the higher the adsorption selectivity.The competitive adsorption selectivity of O₂ is greater than that of N₂ when the O₂/N₂ mixed component is at low pressure（<1 MPa）and O₂ concentration ratio is lower than 20%.The three concentration ratios can provide theoretical parameter selection and guidance for mixed gas injection and goaf concentration detection.（4）The high pressure adsorption experimental device of coal was designed to carry out the secondary adsorption experiment of CO₂ gas by coal.By comparing the experimental data with the simulated data,it is finally proved that the adsorption law obtained by Wiser bituminous coal model can provide reference for the coal samples of qianyingzi coal mine.The adsorption capacity of coal samples is positively correlated with the adsorption equilibrium time.The higher the adsorption equilibrium pressure,the less time it takes to reach the adsorption equilibrium.The activation energy of the original coal sample,dry coal sample and twice adsorbed coal sample is calculated.The combustion activation energy of the four coal samples is secondary adsorbed coal sample>dry coal sample>original coal sample>primary adsorbed coal sample,indicating that the occurrence of spontaneous combustion of coal can be better inhibited only when it is closer to saturated adsorption.There are 39 figures,12 tables and 77 references in this paper.