Study On The Block And Electrichemical Effects Of Coking Coal Methane Adsortion And Desortion

At present domestic about the coal sample blocks of the influence of coalsample gas adsorption desorption experiment, experiment using pulverized coalcoal sample for60mesh commonly the following. Research results show thatthe adsorption ability of coal has nothing to do with fragmentation, coal to gasdesorption quantity, at the same time, the smaller the blocks of coal sample, thelarger the desorption velocity and desorption amount is larger. Greater than6mm when coal sample blocks of coal sample blocks of less research on theinfluence of the coal sample gas adsorption desorption.The change of coal pore structure methods mainly include heating of coalsamples, deal with coal samples with different chemical reagent, etc., this articleadopts the method of electrochemical action of coal sample change the porestructure of coal sample.At present to promote the main technical method of pressure relief of gasdesorption and physical fields. Unloading method of deformation caused bypressure relief and relieve stress barrier to achieve the purpose of promotingdesorption, but as a result of coal to gas adsorption is very strong, make thestress state of coal sample is still difficult to desorption of gas. Therefore, onlyby unloading of coal seam gas desorption effect is limited. Plus physical fieldssuch as sound field, electric field, electromagnetic field and temperature field ina certain extent can promote gas desorption, in order to solve the problems ofthe gas desorption hard provides a new train of thought. This article in view of gas adsorption on coal surface is difficult to fully desorption is the current gasdrainage/CBM extraction from the core of the problem, on the basis ofpredecessors’ research put forward a kind of mechanical method to promotecoking coal gas desorption characteristics of train of thought, i. e., strengtheningof coking coal gas desorption electrochemical properties, and conducted thefollowing research work:(1) By the method of capacity of6different blocks of the coking coaladsorption desorption experiment was carried out, it is concluded that theisothermal adsorption curve and isothermal desorption curve, analysis of degreeof impact on coking coal adsorption desorption. Changes affect the followingconclusions:1) the blocks of the coal samples of gas adsorption is mainlymanifested on the adsorption equilibrium time, the test temperature, adsorptionequilibrium pressure and moisture of coal samples under the same conditions,the smaller the blocks, the less time to reach adsorption equilibrium, on thecontrary, the greater the piece, the more time; Fragmentation changes have littleimpact on the coal sample gas adsorption quantity.2) the influence of the earlychange of coal sample gas desorption speed in two situations: when the coalsample piece of degrees is greater than the limit block, block degree of changewill have little impact on the early coal sample gas desorption speed;When thecoal sample piece is less than the limit block degrees, coal sample for thesmaller pieces, the faster the early stage of gas desorption.3) blocks of changeaffects the quantity of coal sample gas desorption mainly reflected on thedesorption equilibrium time, the test temperature, adsorption equilibriumpressure and moisture of coal samples under the same conditions, differentdegree of coal sample piece of the desorption amount is the same, thedesorption equilibrium time is different, when the coal sample piece is less than the limit block degrees, the smaller the blocks, coal sample gas desorptionequilibrium of the shorter the time, when the coal sample piece is greater thanthe limit block degrees, different blocks of coal sample gas desorptionequilibrium in the same time.(2) By using mercury intrusion method, nitrogen injection test before andafter the modification of coal samples, its porosity, average pore diameter,entrance, specific surface area, the following conclusions:1) in the coal to gasadsorption ability mainly depends on coal pore and pore specific surface area.Electrochemical action after the coal sample’s pore and pore connectivity, thequantity and the specific surface area decreased, therefore, electrochemicaleffect of coal to gas adsorption ability.2) after the electrochemical action of coalsample in the increase in the number of holes and the big hole, porosityincreases, the benefit in coal gas desorption.3) in the process of electrochemicalaction, anode generated H+, form the acid environment, cathode to generateOH-, the formation of alkaline environment, at the same time accompanied byelectroosmosis and electrophoresis, dissolve the coal part of inorganic mineralor remove, and change the pore structure of coal.(3) Through electrochemical action to strengthen coking coal desorptionexperiment, the characteristic of the five kinds of electrolyte concentration, fivekinds of electrochemical potential gradient, the effect of strengthening law ofcoking coal desorption characteristics, the following conclusions:1) theelectrochemical strengthening coking coal gas desorption process, Anodeextreme oxidation reaction, O2, CH4and CO2, the most O2, CH4and CO2issmall; Cathode extreme reduction reaction, generate H2, but Cathode extremeand CH4gas collected, this is because in the process of electrochemical actionhappened electroosmosis effect, bring out the gas in coal.2) under the condition of different electrolyte concentration, electrochemical gas desorptionexperiments, strengthening Anode extreme Cathode and extreme gas dischargerules of basic same, eventually the same amount of gas collection, electrolyteconcentration, the greater the reach final gas collecting shorter amount of time.3) under the condition of different potential gradient, electrochemical gasdesorption experiments, strengthening Anode extreme Cathode and extreme gasdischarge rules of basic same, gas collection quantity increase gradually,eventually reached a fixed value, eventually the same amount of gas collection,the greater the potential gradient, achieve finally gas collecting shorter amountof time.4) electrochemical modification to strengthen the mechanism of coal gasdesorption has two aspects: on the one hand is the electrolysis andelectroosmosis effect from two aspects of "expanding effect" in the coal samplecause aperture, entrance, porosity changes from small to big, from large to smallsurface area. In general, aperture, entrance, the greater the porosity, gasmigration in coal is relatively easy; The smaller the specific surface area, thecoal gas adsorption ability is weak, so that gas molecules to desorption fromcoal. Electrochemical effect on the other hand is to change the number of coalsample surface oxygen containing functional groups, reduce the number of coalsample surface oxygen containing functional groups, make its produce the totalinteraction energy decreases, namely the adsorption potential smaller. From themacro performance for coal adsorption gas ability is abate, coal desorption gasability enhancement.