Experimental Study And Application Of Exoteric Solution On Gas Desorption In Coal

With the improvement of coal mine production level,the prevention and control means of gas accidents have been greatly improved,but gas over-limit still occurs.External leaching solution to inhibit gas desorption is one of the effective ways to solve this problem.However,the effect of external leaching solution on gas desorption is affected by many factors,such as ventilation in roadway,roadway ambient temperature and the type of external leaching solution.In order to study the effect of external leaching solution under the influence of many factors,through the self-developed multi-factor desorption and spraying test-bed of coal gas,the experiment of coal gas desorption under the influence of multiple factors was carried out,and the influence of ambient temperature,coal particle size and the type of external leaching solution on gas desorption effect was analyzed,and the influence law of external leaching solution on coal gas desorption was obtained.Finally,the inhibition effect of external leaching solution on gas desorption is verified by on-site industrial test,which provides data reference for the application of external leaching solution in coal mine to restrain gas desorption and prevent the occurrence of gas out-of-limit accidents.the main conclusions are as follows:(1)A multi-factor coal gas desorption spray test-bed is independently developed,which includes five parts:model main body,air flow system,solution spray system,gas adsorption system and data acquisition system.it can realize the monitoring of gas concentration in different positions under the influence of many factors,such as solution spray,ventilation,temperature,different coal particle size and so on.(2)In the influence range of external leaching solution,the variation curve of gas concentration with time can be divided into two stages:gas accumulation and gas attenuation.Among them,the cumulative peak concentration of gas at each measuring point showed different correlation with ambient temperature,coal particle size and solution type:the peak gas concentration was negatively correlated with coal particle size,positively correlated with ambient temperature and negatively correlated with the mass fraction of leaching solution.(3)The inhibition effect of leaching solution on gas desorption varies with the coal particle size.When the coal particle size is between 2.8 mm-30 mm,the average inhibition efficiency increases with the increase of coal particle size.When the coal particle size is 20mm-30mm,the average gas inhibition efficiency reaches 20.38%.Under the influence of coal particle size,the external leaching solution has the greatest inhibitory effect on gas desorption at the lower corner of the air inlet and the least inhibition at the upper corner of the air inlet.(4)When the ambient temperature is between 25℃ and 45℃,the average peak gas concentration increases from 5838 ppm to 6346 ppm with the increase of ambient temperature,and the ability of external leaching solution to inhibit gas desorption changes with the increase of ambient temperature.The inhibitory effect of external leaching solution on gas desorption is weakened at the lower corner of the air outlet,the upper corner of the air inlet and the lower corner of the air inlet,while the inhibition of gas desorption at the upper corner of the air outlet and the center of the model is enhanced.(5)The concentration of leaching solution will also affect the gas desorption effect.When the mass fraction of the leaching solution is between 0.00%and 0.40%,with the increase of the mass fraction,the inhibitory effect of the external leaching solution on gas desorption is enhanced,and the inhibition efficiency of gas desorption at different positions in the model is improved,the inhibition efficiency is up to 30%.(6)In the field industrial test,the decyl glucoside solution with the best experimental effect was used to wet the coal,and the gas concentration in the working face showed a downward trend,in which the gas concentration on the side near the return roadway decreased obviously,and the gas concentration decreased by 20%.The gas concentration in the upper corner of the return roadway is reduced by 26%.In this paper,through on-site investigation and inquiry,a multi-factor gas desorption spray test bench is developed,and a series of experiments on the influence of external leaching solution on gas desorption are carried out through the research and development test bench.Finally,according to the law obtained from the experimental study,the on-site industrial test of external leaching solution is carried out by using the existing equipment in coal mine,which provides data reference for the prevention and control of gas out-of-limit accidents.