Experimental Study On The Effect Of Coal Enhanced By Supercritical Carbon Dioxide

In order to study of supercritical carbon dioxide antireflective effect on coal,taking two different metamorphic grades coal as the research objects,using the coal enhanced by supercritical carbon dioxide experimental system,the experimental study on effect of coal body permeability enhanced by supercritical carbon dioxide is carried out.The permeability of coal was measured before and after the treatment of supercritical carbon dioxide.The effect of supercritical conditions on the permeability of coal is analyzed.The influence of supercritical carbon dioxide treatment on the microstructure of coal samples is studied through microscopic experiments.The main conclusions of this paper are as follows:(1)Through the study of the treatment time effect on the coal samples by supercritical carbon dioxide,it turns out that when the time after the treatment of supercritical carbon dioxide reaches about 10 hours,the permeability of coal body has been treated well,and increase the treatment time continuously,the permeability change is not obvious;(2)under the condition of the same temperature,when the pressure conditions are changed,it is found that the permeability change of coal samples is very obvious after a supercritical carbon dioxide treatment,and the permeability increases by about 100%,and then increase the pressure continuously,the permeability change is not obvious;(3)under the condition of the same pressure,when the temperature conditions are changed,it is found that the permeability change of coal samples is very obvious after a supercritical carbon dioxide treatment,and then increase the temperature continuously,the permeability change is not obvious;(4)the results of the study on the microstructure before and after the treatment of the coal samples show that,after the supercritical treatment,the surface of the coal samples appeared corroded pits,and the original fracture channel has been extended;the results of mercury injection experiment show that the porosity,pore volume is increased and the specific surface area of the treated coal samples are decreased;Among them,the pore volume of the macro pores and mesopores are increased;however,the specific surface area of the small pores increases,and the specific surface area of micro pores are decreased accordingly.From the above analysis,it can be seen that some small molecular organic compounds of the coal martix is extracted by supercritical carbon dioxide,which can change the pore structure of coal and increase the permeability of coal.