Analysis on coalbed methane desorption stage and calculation on max instant desorption value of tectonic coal

In order to research the coalbed methane desorption stage and desorption instant features of the tectonic coal,the tectonic coal and in- situ structure coal fr om Pingdingshan No. 5 Mine were selected,a methane isothermal adsorption 1 desorption test was conducted under temperature of 20、30、 40。C individually. Based on th e test,a coalbed methane desorption stage model was established based on Langmuir equation curvature and was applied to analyze the coalbed methane desorption stag e of the tectonic coal and discuss the max instant desorption value of the coalbed methane from the tectonic coal. The results showed that with the temperature steadily inc reased and the coal failure degree increased,a low efficient desorption stage,slow desorption stage,high efficient desorption stage and sensitive desorption stage of the in- situ structure coal and tectonic coal would move to the low pressure direction generally,and the start pressure,turning pressure and sensitive pressure would be in a reducti on tendency. In comparison with the in- situ structure coal,the major start pressure and turning pressure of the tectonic coal would be more lower and the total desorption s tage would have more obvious to low pressure moving features. On the other hand,the large Langmuir volume would be favorable to the high efficient desorption and sensit ive desorption early coming. Meanwhile,with the temperature increased,the max desorption value of the coalbed methane from the in- situ structure coal and tectonic coal would be in a small reduction tendency.