Experimental Study On Initial Stage Features Of Gas Desorption Of Tectonic Coal

Tectonic coal with low intensity, high energy storage, rapid desorption and low permeability are caused to the coal and gas outburst. The characteristics of tectonic coal are the important reason of gas accumulation, which to cause the coal mine disasters, and that is the essence reason of can not determinate gas content accurately and difficult extract CBM directly.The research core is initial stage features of tectonic coal gas desorption,which based on the structure of coal. The test device has designed and experimental studies of initial stage features of gas desorption of Hebi, Pingdingshan tectonic coal and undeformed coal have been tested. Then analysed the influence factors and established the tectonic coal gas initial desorption model, at last discussed the gas loss compensation method in gas content determination.The main conclusions are as follows:(1) The adsorption ability of tectonic coal and undeformed coal in the same place, however, the ability of tectonic coal gas desorption in initial stage is far greater than undeformed coal. The desorption rate and relationship meet Q=At^-b and the desorption and desorption time curve consistent with V_t = At^b during the 0 to 3minutes.(2) Tectonic coal has large desorption speed and quick decline. Initial stage gas desorption of tectonic coal and undeformed coal differences mainly manifested at first minute. Tectonic coal gas desorption rate distribution range is 1.225 4.197 ml/ (g·min) which is 1.25².84 to undeformed coal,which desorption rate distribution range is 0.485³.683 ml/ (g ? min). Experiments showed that construction of coal gas desorption before the 10s, 30s, 1min, 3min, 10min gas volume To 60min the proportion of the gas desorption, respectively: 16%, 24%, 31%, 45% and 64%.(3) The curve of initial stage gas desorption of tectonic coal and undeformed coal always formulated a monotonic decreasing function. The bigger particle size the lower desorption speed, the higher adsorption balance pressure the higher desorption speed, the higher the damage degree of coal the little more influence to desorption speed.(4) Compered determination data of features of with the existing empirical formula, 0-3minute of tectonic coal initial stage gas desorption laws are draw up to match effective Winter type. Initial stage features of tectonic coal gas desorption and desorption time showed linear relationship, fitting: Ln (V t ) = BL n(t )+ cunder the bi-logarithm coordinates.(5) According to the experimental results, analysis the influence factors of tectonic coal initial desorption factors. Metamorphism not only produced gas but also reshaped the pore structure of tectonic coal, which transformed macropore to mesopore and micropore, and which from open hole to closed hole along with the produce deformity hole. Distribution characteristics of mesopore and micropore decide the ability of initial stage features of tectonic coal gas desorption. Between size and quantity of gas desorption with equation: Qt = ax²+ bx + c.With the increasing of desorption time, a c increased but b decreased. Between Adsorption gas balanced pressure and desorption speed meet: V₁ = B·P^k_p.(6) Puts forward the piecewise functions of tectonic coal gas desorption. And consider that the tectonic coal 0-3min gas desorption characteristics formula should be expressed as follows:Better effects after experimented, and can be used for engineering application.