Experimental Study On The Influence Of Microwave Radiation On The Permeability Of Coal

It is a new research field to apply microwave heating technology to coalbed methane mining.A lot of theoretical research needs to be further improved.In order to study the relationship between permeability and microwave power deeply,radiation time and effective stress under microwave radiation conditions,the paper uses Self-developed microwave radiation containing gas coal seepage experimental system and scanning electron microscope equipment to develop macroscopic and microscopic experiments,then from macroscopic and microscopic perspectives,and finally combined with relevant theoretical basis for comparative analysis of experimental data,the analysis results are as follows:Firstly,the changes of coal structure before and after microwave irradiation are studied by means of scanning electron microscopy.The changes of coal sample microstructure and size before and after microwave irradiation are compared,and the size change curve is drawn.The comprehensive comparative analysis shows that microwave irradiation has a certain influence on the micro-pore-fracture structure of coal,mainly on the role of microwave in coal cracking and pore opening.With the prolongation of microwave action time,it can be found that secondary development of pore-fissure structure in coal samples,and the original pore-fissure structure of coal samples expands and new pore and fissure can be produced.At the same time,it can be found that the influence of high microwave power on coal structure is more obvious.Secondly,through the establishment of microwave radiation gas-bearing coal seepage experimental system,under different microwave conditions,the macro-seepage experiments of coal samples are carried out.Through fitting the experimental data,it is found that the relationship between permeability and effective force satisfies the negative exponential function,and the fitting results R~2are greater than 0.98,which are consistent with the classical permeability curve.It is found that the permeability of coal sample is positively correlated with microwave action time and microwave power.When the same microwave energy input is controlled in the experiment,the microwave magnetic field intensity increases due to the increase of microwave power.Compared with the microwave action of long time and low power,the permeability of coal sample increases more obviously in short time and high power microwave action.Combining with the experimental data,it is also found that reducing the effective stress in the environment of coal sample is helpful to the effect of microwave seepage enhancement in the process of microwave action.Finally,combined with the analysis of macroscopic seepage experiments and microstructure scanning experiments,it is found that the increase in microstructure of coal body under microwave irradiation leads to the increase of coal porosity and the increase of macroscopic permeability of coal after microwave microwave irradiation.The conclusions coincide with each other,and the macroscopic and microscopic experimental results are mutually confirmed.The research results will help to further understand the laws of the changes of coal permeability under microwave action and provide a theoretical reference for the application of microwave radiation technology in the field of coalbed methane mining,then provide a theoretical basis for the application of microwave technology to realize the industrial exploitation of coalbed methane.The paper has 46 pictures,22 tables,and 89 references.