Study On Adsorbent For Pressure Swing Adsorption Separature Of Coal Mine Ventilation

For methane enrichment and separation of ventilation air methane （VAM） in coalmine, carbon adsorption material was studied by supported metal modification,roasting modification, KOH modification for pressure swing adsorption （PSA）.Adsorbent industrialization preparation and pilot scale experiment were carried.The separation factor α, selectivity coefficient of adsorption capacity W,adsorption selection parameter S and adsorption amount of capacity V were selectedas the evaluation parameters. The pore size, pore volume, surface area were taken asreference. Carbon material adsorbent was screened for modification. PA-1wasselected for supported metal modification,10²0mesh coconut shell charcoal forroasting modification, KOH modification. ZC1326was chosen as the most suitableACF material.The metal ions for PA-1modification were chosen by hydrothermal method, inwhich Ti modification was particularly prominent. The evaluation of adsorbent wastaken according as separation factor, selectivity coefficient of adsorption capacity,adsorption selection parameter and adsorption capacity of CH4at150kPa. Andatmospheric penetration test was taken to evalute adsorption properties of adsorbentmodified. The separation factor α changes from4of PA-1to4.3of Ti-PA-1-160℃andto3.9of Ti-PA-1-160℃-1100℃, selection coefficient of adsorption capacity W alsodecreases from2.8of PA-1and Ti-PA-1-160℃to2.2of Ti-PA-1-160℃-1100℃,corresponding adsorption selection parameter S is11.20,12.04and8.58, but itsmethane adsorption amount V at150kPa increases from22.7cm³/g to34.4cm³/g,increasing51.5%. Breakthrough point of atmospheric penetration curve is111s forTi-PA-1-160℃-1100℃. Respectively, it was lagged by41%and50%compared withPA-1and Ti-PA-1-160℃. Sr modified activated carbon shows very low adsorptionproperties of N₂.Coconut shell activated carbon modified by KOH and activated carbon mixedmethod, activated carbon fiber modified by KOH solution dipping method. WhenKOH:C was2:1, carbonization temperature and activation temperature were500℃and800℃, of carbonizationtime and activation time were1h and2H, modified ACadsorption properties were the best. CH4adsorption amount V reaches51.6cm³/g,separation factor α is4.2, selection coefficient of adsorption capacity W is2.5and adsorption selection parameter S is10.50. Respectively, changes are+63.8%,-10.6%,+4.2%and-6.9%than the unmodified activated carbon. When KOH concentration is13%, activation time is40min, activation temperature is800℃, modified ACFadsorption properties were the best. Separation factor α is4.2, selection coefficient ofadsorption capacity W is2.4, and adsorption selection parameter S is10.08.Parameters decreases4.5%,11.1%and15.2%than the unmodified, but CH4adsorption capacity V reaches49.4cm³/g and increases48.3%than the unmodified.Roasting method was adopted for AC modification. The effects of roastingtemperature, roasting time and roasting atmosphere on coconut shell charcoalseparation of CH4/N₂and physical performance were studied. In the experiment, thebetter condition is found that it is roasted at600℃for4H in N₂atmosphere. In thiscondition, modified coconut shell charcoal has no obvious change on physicalproperties and has good separation performances. Separation factor α is4.8,increasing2.1%than4.7of unmodified AC; selection coefficient of adsorptioncapacity W is2.2, reducing8.3%than2.4of unmodified AC, adsorption selectionparameter S is10.56, reducing6.4%than11.28of unmodified AC, CH4adsorptioncapacity V reaches36.0cm³/g, increasing14.3%than31.5cm³/g of the unmodified AC.Breakthrough point of atmospheric penetration curve is172s and lagged by212.7%compared with55s of the unmodified AC.Adsorbent industrialized preparation process is roasting at650℃for4h in N₂atmosphere, dipping in1mol/LHCl solution for24h, washing and drying. Activatedcarbon after drying is3745kg, and the total loss weight is22.4%. A test device wasbuilt for coal mine VAM enrichment and separation. The volume of feed gas is1000m³/h. Using ventilation air reduction device, the maximum concentration of CH4can reach0.3%in export center after hydrocyclone enrichment. When the CH4average concentration is about0.2%, the CH4concentration of export for adsorptionseparation and enrichment system is larger than or equal to1%, the recovery rate canreach about50%.