Study On The Block And Electrochemical Effects Of Anthracite Coal Gas Desorption

In the field of CBM exploitation, China is still in its infancy, all the technology is not mature enough, especially in China’s Coal Geology special characteristics of "three lows and one high" caused by low desorption of coal seam, low permeability, has been restricted to bed methane extractionkey issues. Therefore, improving the gas desorption and permeability in the coal seam, improved extraction technology become the key part of China’s CBM exploitation. This paper analyzes on the present situation of coal coal gas desorption characteristics and electrochemical at home and abroad, and puts forward a new kind of method to improve the non-mechanical effects of coal gas desorption, basic research idea and theory of electrochemical enhanced coalbed methane desorption, and the main research work is as follows:1. In the independent development of coal gas adsorption and desorption device, isothermal gas desorption experiments of0.8mm～1mm,8mm～10mm,20mm～25mm,40mm～45mm,70mm～75mm and135mm～140mm six blocks of anthracite had been done in different gas adsorption balance pressures.2. In the block coal electrochemical device of independently developed, the electrochemically modified test of the six block of anthracite has been done.3. Through the analysis of desorption data of six blocks of natural anthracite, With the block of anthracite increased, desorption velocity and desorption rate decreases gradually, desorption time extend gradually; With the increase of gas adsorption pressure, capacity of coal gas desorption increased gradually, but the increase rate decreases.4. Through the analysis of desorption data of six blocks of electrochemical anthracite, found the block of0.8mm-lmm anthracite desorption rate is larger than that of other five kinds of block coal desorption velocity after the electrochemical action, and with the block increase desorption velocity decreased gradually but the difference was not significant fragmentation; There is relationship between the gas desorption characteristics of anthracite coal and gas adsorption pressure after electrochemical action:With Methane adsorption pressure increases, the the coal gas desorption capacity is gradually increased, but at the Methane adsorption pressure of2MPa and3MPa, desorption did not change significantly.5. Through the analysis of desorption data of six blocks of anthracite before and after electrochemical, found anthracite by electrochemical action at block of0.8mm to1mm desorption velocity did not change significantly, while the other block coal after electrochemical action the desorption velocity are improved and block more desorption rate increased more obvious; anthracite by electrochemical action at block of0.8mm to1mm desorption rate decreased obviously, The remaining five blocks anthracite by electrochemical action desorption rate increased.6. Through the analysis of mercury injection data on0.8mm～1mm and8mm～10mm two kinds of block natural anthracite, found the8mm～10mm of coal mesoporous and macroporous ratio was more than the0.8mm～1mm of coal sample, indicating the proportion of pores and holes in the large degree of coal samples has been declined;0.8mm～1mm and8mm～10mm two block of anthracite coal sample specific surface area are respectively1.330m2/g and6.415m2/g, indicating bulk of coal sample specific surface area increased significantly. Speculation:anthracite gas desorption velocity is determined by the amount of coal sample of mesoporous and macroporous; while the anthracite surface area determines the gas desorption rate.7. Through the analysis of the original coal sample,0.8mm～1mm block modified anthracite and8mm～10mm block modified anthracite kind of FTIR map, found anthracite’s phenols, ethers, alcohols, esters and other oxygen-containing functional groups decreased rapidly is the direct cause of anthracite gas desorption rate increased after electrochemical action; while0.8mm～1mm and8mm～10mm two kinds of block modified coal samples had no obvious differences, indicating with the increase of modified coal sample block, the electrochemical effect of anthracite decreases, macroscopically with increasing size, gas desorption rates decreased, but the decrease amplitude decreases gradually.