NIOSHTIC-2 Publications Search
Adsorption of methane/ethane mixtures on dry coal at elevated pressure.
Ruppel TC; Grein CT; Bienstock D
Fuel 1972 Oct; 51(4):297-303
The binary adsorption characteristics of methane and ethane on dry coal to 40 atm pressure have been calculated from pure-component isotherms. In some coal seams, pressures exceeding 40 atm have been recorded and the methane sampled from the virgin coal often shows a few percent of ethane. The binary adsorption characteristics were calculated by employing the ideal adsorbed solution theory of Myers and Prausnitz, and experimentally-determined (Type I) pure gas isotherms at 0, 30 and 50 degrees C. The coal used in this investigation was high-volatile 'A' bituminous (hvab) from the Pennsylvania Pittsburgh seam. Gas nonideality was accounted for by replacing pressure with fugacity. Adsorption of methane on dry coal is purely physical; the isosteric heat of adsorption does not exceed 2.4 kcal/mol* at 30 degrees C on the above coal. Isobars on the resulting binary equilibrium diagram exhibited an unexpected phenomenon of intersecting each other which might be attributable to the above nonideality considerations. The region of a few percent of ethane, which is of practical importance from the viewpoint of coal seams, was expanded and reduced to an equation: V(CH4) = -21.52 + 7.18(VF) + 16.88(VF)2 -0.395(P) - 0.00661(P)2 + 0.824(T) - 0.00030(T)2 + 0.928(VF)(P) - 0.858(VF)(T). V(Total) = 25.9 - 23.6(VF) + 0.655(P) - 0.00875(P)2 - 0.795(T) + 0.743(VF)(T) where V(CH4) and V(Total) = cm3(STP)CH4 and total gas respectively adsorbed per g dry coal; VF = vol. fraction of methane as analysed at 1 atm (0.94 ≤ VF ≤ 1.0); P = seam pressure, atm (0 ≤ P ≤ 40); T=seam temperature, degrees C(-10 ≤ T ≤ 50).
Adsorption; Gas mixtures; Coal seams; Coal gas; Methanes; Ethanes; Bituminous coal; Atmospheric pressure
Issue of Publication
Page last reviewed: May 20, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division