松散煤体内CO2渗流规律试验

1.西安科技大学 安全科学与工程学院,陕西 西安 710054; 2.西安科技大学 陕西省煤火灾害防治重点实验室,陕西 西安 710054

传质传热; 非线性渗流; 密度; 渗透率; 非达西因子

Study on seepage law of CO2in loose coal
ZHAI Xiao-wei1,2,XU Yu1,2,YU Zhi-jin1,2,WANG Kai1,2,WU Shi-bo1,2

(1.College of Safety Science and Engineering,Xi'an University of Science and Technology,Xi'an 710054,China; 2.Shaanxi Key Laboratory of Prevention and Control of Coal Fire,Xi'an University of Science and Technology,Xi'an 710054,China)

mass and heat transfer; nonlinear seepage; density; permeability; Non-Darcy factor

DOI: 10.13800/j.cnki.xakjdxxb.2018.0305文章编号: 1672-9315(2018)03-0375-08

备注

利用液态CO2进行煤矿火灾防治,具有显著的惰化降温效果,而松散煤体内CO2的渗流是分析其传质传热过程的基础。为分析承压状态下CO2气体的物性参数特征以及松散煤体内渗流规律,采用松散煤体渗透系数测定装置,对不同粒径、压注压力和孔隙率下CO2气体的渗透特性进行了试验。结果 表明:松散煤体中的CO2渗流存在明显的非线性渗流特征,符合非达西理论; 孔隙率小的煤样压力梯度大于孔隙率大的煤样,颗粒间的空隙是渗流的主要通道; 相比于孔隙率和压力,煤体粒度是影响渗流特征关键因素,煤体粒径越小,CO2在松散煤体中渗流越困难; 压注压力越大,CO2密度和动力粘度越大,导致CO2在煤体中渗透率增大,而非达西因子减小,因此对CO2在松散煤体中的渗流影响不大。通过数据拟合,CO2的渗透率和非达西因子与孔隙率、粒径成幂指数关系,并得到了基于粒度和孔隙率下用于描述松散煤体内CO2气体渗流的一般理论方程。

The liquid CO2 is helpful for prevention and control of coal mine fire,which has a significant inert and cooling effect on the fire.And the seepage law of CO2 in loose coal is the basis for analyzing the process of heat and mass transfer.In order to analyze physical parameters of CO2 gas and its seepage law in loose coal under pressure conditions,an experimental apparatus for testing the permeability coefficient of loose coal is established and the permeation characteristics of CO2 gas are tested with the apparatus under different particle diameters of coal,pressures and porosities.The result shows that the seepage characteristics of CO2 in loose coal is obviously non-linear,which is in accord with non-Darcy theory; The pressure gradient of coal sample with small porosity is larger than that of coal sample with large porosity,and the gap between particles is the main channel of seepage; Compared with the porosity and pressure,the particle diameter of coal is a key factor influencing the seepage characteristics.The smaller the coal particle size,the more difficult it is for CO2 to seep in the loose coal; The density and the dynamic viscosity of CO2 increase with injection pressure,and the permeability of CO2 increases in the coal body while the non-Darcy factor decreases,so it has little effect on the seepage of CO2 in loose coal.Data fitting result indicates that both the permeability and the non-Darcy factor are exponentially related to porosity and particle size,and the general theoretical equation for describing CO2 gas seepage in loose coal is obtained based on particle size and porosity.