Coal particle gas adsorption mathematical model and numerical solution under variable pressures

QIN Yue-ping; WANG Jian; ZHENG Yun; TONG Xing; LIU Peng; QI Yi-pei

doi:10.13225/j.cnki.jccs.2016.0913

Abstract：In order to verify the universality of Darcy law in coal particle gas flow,the coal particle gas adsorption experiment in enclosed space under variable pressures was designed on the basis of the constant pressure adsorption and desorption and variable pressure desorption experiments of different coal particles shapes.And the gas accumulative adsorption amount with time variation of 42.976,11.600 ～ 13.800,3.350 ～ 4.000 and 1.180 ～ 1.400 mm coal particles under 0.5,1,2 and 4 MPa initial pressures were obtained.Based on Darcy and Fick law,the gas adsorption mathematical models were proposed separately.The use of finite difference method,combined with the computer progTam coded in Visual Basic,enabled to solve the equations.And the gas accumulative adsorption amount of two models at different times and different initial gas pressures were obtained.By comparing and analyzing ln [1-(Qt/Q∞)2] vs.t diagrams from experiment and numerical simulation,it is found that the gas adsorption process of coal particles in the enclosed space also follows Darcy's law.This conclusion is consistent with a series of previous researches,namely whether the adsorption or desorption process,and the coal particle external pressure and the coal particle shape change or not,it is concluded that Darcy law is the basic rule of coal particle gas flow.