基于改进瓦斯解吸实验方法的初始粉煤快速解吸机理研究

Research on the mechanism of initial rapid desorption of pulverized coal based on an improved gas desorption experimental method

粉煤瓦斯解吸实验是研究粉煤瓦斯解吸动力学特征的常用手段之一,其结果是揭示粉煤放散瓦斯能力的重要参数。传统实验方法在煤样罐泄压后开始测量瓦斯解吸数据,存在较大误差。利用甲烷与氦气的粉煤吸附特性差异性提出了改进的粉煤瓦斯解吸实验方法,并建立了初始瓦斯粉煤快速解吸模型,从而揭示了煤体粉化后瓦斯快速解吸的内在机制。研究结果表明:解吸开始的前5 s,0.075~0.150 mm JG71煤样解吸的瓦斯量是1.00~2.36 mm煤样的2.05倍,而0.075~0.150 mm JG82煤样解析的瓦斯量是1.00~2.30煤样的10.29倍;煤样粉化程度越高,吸附平衡压力越大,初始瓦斯解吸速度越大,传统实验方法得到的数据误差越大。研究结果为突出粉化煤体快速解吸瓦斯、提供瓦斯膨胀能、促进煤与瓦斯突出传播的研究提供了数据支撑,同时为完善煤与瓦斯致灾机理奠定基础。

[Objective]The gas desorption experiment on pulverized coal is a commonly used method to study the kinetic characteristics of gas release from pulverized coal,with the results serving as an important parameter of the coal's gas release capacity.Traditional methods commence the collection of gas desorption data after the coal sample tank is depressurized,so neglecting the gas volume desorbed during the depressurization stage.This oversight has been identified to lead to a large error in the pulverized coal gas desorption laws of pulverized coal measured by traditional experimental methods owing to the initial phase of desorption being the fastest.[Methods]To capture the accurate gas desorption characteristics of pulverized coal,including desorption in the pressure relief stage,this research proposes an improved experimental method of gas desorption from pulverized coal.This approach utilizes the different adsorption behaviors of methane and helium in pulverized coal.By conducting two simultaneous desorption experiments,it is possible to quantify the gas volume desorbed during the pressure relief stage.Upon obtaining accurate gas desorption characteristics,an initial rapid gas desorption model for pulverized coal was established.This model,combined with experimental data,revealed the intrinsic mechanism behind rapid gas desorption after pulverization of the coal body.[Results]The results indicate that traditional experimental methods cannot obtain the desorption data in the first 5 s of the gas desorption from pulverized coal,where the discrepancy is more pronounced in samples with smaller particles,reaching a 67.74%error in initial desorption rates.The degree of pulverization of the coal samples affects the adsorption equilibrium pressure and the rate of initial gas desorption.In the first 5 s of desorption,the amount of gas desorbed from the JG71 coal sample(particle size 0.075~0.150 mm)was 2.05 times higher than the 1.00~2.36 mm coal sample,and for the JG82 coal sample,it escalated to 10.29 times.The initial rapid desorption model of pulverized coal illustrates that the initial gas desorption volume is inversely proportional to the particle size of the coal sample,the smaller the particles,the faster the initial desorption rate.Notably,as d approaches 0,Qt tends to infinity.[Conclusion]The results provide a method to accurately measure the gas desorption data,which serves a dual purpose.On the one hand,it can assess the coal body's ability to release gas and evaluate the risk of coal and gas outbursts from the coal seam.On the other hand,it can quantify the rapid desorption of gas from an outburst pulverized coal body.This provides theoretical support for accurately calculating the outburst gas emission characteristics and simulating the propagation of coal and gas outbursts,laying the groundwork for improving and enriching our understanding of the disaster-causing mechanisms behind coal and gas outbursts.