颗粒煤甲烷吸附过程扩散特征

Diffusion characteristics of methane adsorption process in granular coal

为了研究甲烷在颗粒煤中扩散、吸附至平衡过程的扩散特性,基于颗粒煤吸附甲烷幂函数扩散模型,利用磁悬浮天平高压等温吸附仪,测定不同压力下颗粒煤甲烷吸附过程中扩散量随时间变化值,研究颗粒煤甲烷吸附达到平衡前的扩散特征。实验结果表明:平衡压力对颗粒煤甲烷吸附和扩散特性影响显著;吸附量和平均扩散系数随着压力增大而增大;颗粒煤甲烷吸附过程扩散系数随时间呈幂函数衰减,前500 s衰减幅度较大,平均扩散系数与时间呈负相关关系。研究认为颗粒煤吸附甲烷幂函数扩散模型对于描述颗粒煤甲烷吸附扩散过程具有较高准确性,有助于分析煤层气排采过程煤层气吸附量的动态变化,提高煤层气采收率。

In order to study the diffusion characteristics of granular coal in methane adsorption process,based on the power function diffusion model of adsorbed methane in granular coal and using magnetic suspension balance high pressure isothermal adsorption instrument,the change of diffusion amount with time during the process of adsorption of methane by granular coal under different pressure was determined and the diffusion characteristics of methane adsorbed by granular coal before equilibrium were studied.The result shows:the equilibrium pressure has a significant influence on the adsorption and diffusion characteristics of granular coal,the adsorption capacity and average diffusion coefficient increase with the increase of pressure.In the process of adsorption of methane by granular coal,the diffusion coefficient decays as a power function over time,and decays greatly in the first 500 seconds,and the average diffusion coefficient is negatively correlated with time.Research suggests particle diffusion model for describing particle coal methane adsorption power function of coal methane adsorption diffusion process with high accuracy,will contribute to analyze the dynamic changes of the coalbed methane mining process of coalbed methane adsorption quantity drained,enhancing coalbed methane recovery.