CO Distribution Pattern In The Corner Of The Working Face Under The Effect Of Cubic Air Leakage

In recent years,during the mining process of coal seams in shallow buried mines in northern Shaanxi province,due to the serious influence of coal seam mining,it is easy to form linked fissures with the surface,which generates wind leakage channels between upper and lower wells,intensifying the degree of wind leakage in the mining area,leading to the increase of oxygen concentration inside the mining area and increasing the risk of coal spontaneous combustion.In this paper,we take 122108 header working face of 2^-2 coal seam in Caojiatan mine as the research object,and use SF₆ tracer gas to observe the surface wind leakage in the mining area in different seasons,compare and analyze the seasonal characteristics of temperature difference and pressure change above and below the well,and calculate the surface wind leakage flow rate by theoretical formula to study the surface wind leakage law in the mining area in different seasons The method of calculating the surface wind leakage flow rate by theoretical formula is used to study the surface wind leakage pattern in the mining area in different seasons.Combined with theoretical analysis and field measurement,the range of variation of the maximum value of wind leakage flow velocity of each measurement point in different seasons was obtained,and the distribution rules of the average wind leakage flow velocity of SF₆ release points at different distances from the mining face in different seasons and the distribution characteristics of the average wind leakage flow velocity of measurement points at different locations on the surface fissure working face in different seasons were compared,and the maximum value of the equivalent hydraulic fissure width at different measurement point locations on the working face in different seasons was calculated by theoretical formula.The range of variation is calculated by theoretical formula,and the comprehensive analysis shows that the fissure development between different locations of the working face is particularly serious in winter season,and the degree of wind leakage can reach the maximum.According to the production characteristics of 122108 working face,the process of CO generated from the oxidation of floating coal in the mining area was monitored by the pre-buried beam pipe method,and the degree of influence of CO gas generated from the oxidation of floating coal in the mining area on the upper corner area was analyzed,and the comprehensive analysis concluded that the main source of CO in the corner area on the working face was generated from the oxidation of floating coal in the mining area.According to the on-site gas monitoring data,the "three zones" of coal spontaneous combustion are divided by the oxygen concentration method and the air leakage intensity at both ends of the working face is measured by the theoretical formula,and the change law of horizontal air leakage at the working face under the actual three-dimensional air leakage conditions is obtained.By CFD simulation,the distribution of horizontal air leakage at the working face under single horizontal air leakage condition is obtained.The characteristics and effects of CO generation from coal oxidation under different experimental conditions are analyzed through the warming experiments of coal spontaneous combustion procedure under different variable conditions.For the characteristics of surface air leakage in the working face mining area of shallow buried coal seam mines and its field measurement law,numerical simulation of wind velocity field and gas concentration field in the working face mining area and its upper corner was carried out using FLUENT software,and the CO distribution law in the corner of the working face under the effect of three-dimensional air leakage was compared and analyzed according to the numerical simulation results of two models under the conditions of single horizontal air leakage and three-dimensional air leakage.